Editing Mercer County, New Jersey

{{short description|County in New Jersey, United States}}
{{Use American English|date=April 2020}}
{{Use mdy dates|date=April 2024}}
{{Infobox U.S. county
 | county               = Mercer County
 | nickname             = ''The Capital County''<ref name=MercerCapitalCounty>{{cite web|url=https://www.mercercounty.org|title=Mercer County "The Capital County"|publisher=County of Mercer, New Jersey|accessdate=September 15, 2021}}</ref>
 | state                = New Jersey
 | type                 = [[List of counties in New Jersey|County]]
 | ex image             = New Jersey State House.jpg{{!}}border
 | ex image cap         = The [[New Jersey State House]] and its golden dome in [[Trenton, New Jersey|Trenton]] in 2006
 | ex image size        = 300px
 | seal                 = Mercer County New Jersey.svg
 | flag                 = Flag of Mercer County, New Jersey.gif
 | founded year         = 1838
 | named for            = [[Hugh Mercer]]
 | leader_title         = [[County executive]]
 | leader_name          = [[Daniel R. Benson]] ([[Democratic Party (New Jersey)|D]], term ends December 31, 2027)
 | seat                 = [[Trenton, New Jersey|Trenton]]<ref name=CountyMap/>
 | largest city         = [[Hamilton Township, Mercer County, New Jersey|Hamilton Township]] (population)<br />[[Hopewell Township, Mercer County, New Jersey|Hopewell Township]] (area)
 | city type            = municipality
 | area_total_sq_mi     = 228.86
 | area_land_sq_mi      = 224.44
 | area_water_sq_mi     = 4.42
 | area percentage      = 1.9
 | area_footnotes       = <ref name=CensusArea/>
 | population_as_of     = 2020
 | population_total     = 387340
 | population_footnotes = <ref name=Census2020/><ref name=LWD2020/>
 | pop_est_as_of        = 2024
 | population_est       = 392138 {{increase}} 
 | pop_est_footnotes    = <ref name=Census2020/><ref name=PopEst/>
 | population_density_sq_mi=auto
 | population_density_km2 = auto
 | coordinates          = {{coord|40.28|-74.70|display=inline,title|type:adm2nd_region:US-NJ_source:UScensus1990}}
 | district             = 3rd
 | district2            = 12th
 |website={{url|mercercounty.org}}|time zone=Eastern}}

'''Mercer County''' is a [[County (United States)|county]] located in the [[U.S. state]] of [[New Jersey]]. Its [[county seat]] is [[Trenton, New Jersey|Trenton]], also the [[List of capitals in the United States|state capital]],<ref name=CountyMap>[https://www.nj.gov/state/archives/catctytable.html New Jersey County Map], [[New Jersey Department of State]]. Accessed December 22, 2022.</ref> prompting its nickname '''The Capital County'''.<ref name=MercerCapitalCounty/> Mercer County alone constitutes the Trenton–Princeton [[Metropolitan Statistical Areas of New Jersey|metropolitan statistical area]]<ref>[https://bidenwhitehouse.archives.gov/wp-content/uploads/2020/03/Bulletin-20-01.pdf Revised Delineations of Metropolitan Statistical Areas, Micropolitan Statistical Areas, and Combined Statistical Areas, and Guidance on Uses of the Delineations of These Areas]</ref> and is considered part of the [[New York metropolitan area#Combined statistical area|New York combined statistical area]] by the [[United States Census Bureau|U.S. Census Bureau]],<ref name=omb20180904>(Note: Mercer County, NJ is NOT part of the Philadelphia CSA according to this original source.) [https://bidenwhitehouse.archives.gov/wp-content/uploads/2018/09/Bulletin-18-04.pdf "Revised Delineations of Metropolitan Statistical Areas, Micropolitan Statistical Areas, and Combined Statistical Areas, and Guidance on Uses of the Delineations of These Areas", OMB Bulletin no. 18-04, The White House, Office of Management and Budget, September 4, 2018]</ref><ref>[https://www2.census.gov/geo/maps/metroarea/stcbsa_pg/Feb2013/cbsa2013_NJ.pdf NEW JERSEY - Core Based Statistical Areas (CBSAs) and Counties] {{webarchive|url=https://web.archive.org/web/20170723172037/https://www2.census.gov/geo/maps/metroarea/stcbsa_pg/Feb2013/cbsa2013_NJ.pdf |date=July 23, 2017 }}, [[United States Census Bureau]], February 2013. Accessed August 8, 2017.</ref><ref>[https://www2.census.gov/geo/maps/metroarea/us_wall/Jul2015/csa_us_0715.pdf Combined Statistical Areas of the United States and Puerto Rico] {{webarchive|url=https://web.archive.org/web/20180430005624/https://www2.census.gov/geo/maps/metroarea/us_wall/Jul2015/csa_us_0715.pdf |date=April 30, 2018 }}, [[United States Census Bureau]], July 2015. Accessed August 8, 2017.</ref> but also directly borders the [[Delaware Valley|Philadelphia metropolitan area]] and is included within the [[Federal Communications Commission]]'s Philadelphia Designated Media Market Area.<ref name="FCC DMA Current">[http://transition.fcc.gov/dtv/markets/maps_current/Philadelphia_PA.pdf - Philadelphia Market Area Coverage Maps] {{webarchive|url=https://web.archive.org/web/20140524023753/http://transition.fcc.gov/dtv/markets/maps_current/Philadelphia_PA.pdf |date=May 24, 2014 }}, [[Federal Communications Commission]]. Accessed December 28, 2014.</ref> The county is part of the [[Central Jersey]] region of the state.<ref>[https://www.nj.gov/governor/news/news/562023/20230824a.shtml Governor Murphy Settles Central Jersey Debate], [[Governor of New Jersey]] [[Phil Murphy]], press release dated August 4, 2023. "Governor Phil Murphy today signed S3206 to promote Central Jersey tourism.... The 'Central Jersey' region will be comprised of, at minimum, the counties of Hunterdon, Mercer, Middlesex, and Somerset."</ref><ref>Willis, David P. [https://www.app.com/story/news/local/new-jersey/2023/02/20/central-jersey-debate-ocean-union-county-nj/69914996007/ "'This is how wars start': Does Central Jersey include both Ocean and Union counties?"], ''[[Asbury Park Press]]'', February 20, 2023. Accessed March 31, 2024. "North Jersey is defined as Sussex, Warren, Morris, Passaic, Bergen, Essex and Hudson counties; South Jersey would be Burlington, Camden, Gloucester, Atlantic, Salem, Cumberland and Cape May counties. But for Central, things get a little tricky. It would include Hunterdon, Somerset, Union, Middlesex, Mercer, Monmouth, and Ocean counties."</ref><ref>[https://bestofnj.com/nj-regions-page/ "Regions: North, Central, South, Shore - Best of NJ"], ''Best of NJ'', Accessed May 30, 2024. "Central Jersey consists of Hunterdon, Mercer, Middlesex, Somerset, and Union County."</ref>

As of the [[2020 United States census]], the county retained its position as the state's [[List of counties in New Jersey|12th-most-populous county]],<ref name=Largest2020>[https://www.nj.gov/labor/labormarketinformation/assets/PDFs/census/2020/2020%20pl94%20Tables/2020_PL94_Summary/Table_1_2020.xlsx Table 1. New Jersey Counties and Most Populous Cities and Townships: 2020 and 2010 Censuses], [[New Jersey Department of Labor and Workforce Development]]. Accessed December 1, 2022.</ref> with a population of 387,340,<ref name=Census2020/><ref name=LWD2020/> its highest [[United States census|decennial count]] ever and an increase of 20,827 (+5.7%) from the 366,513 recorded at the [[2010 United States census|2010 census]],<ref name=Census2010/> which in turn had reflected an increase of 15,752 (+4.5%) from the 350,761 enumerated at the [[2000 United States census|2000 census]]<ref name=Census2000>[https://archive.today/20200212082600/http://factfinder.census.gov/bkmk/table/1.0/en/DEC/00_SF1/DP1/0500000US34021 DP-1 - Profile of General Demographic Characteristics: 2000; Census 2000 Summary File 1 (SF 1) 100-Percent Data for Mercer County, New Jersey], [[United States Census Bureau]]. Accessed January 21, 2013.</ref><ref name=Census2010LWD>[http://lwd.dol.state.nj.us/labor/lpa/pub/lmv/LMV_1.pdf NJ Labor Market Views] {{webarchive|url=https://web.archive.org/web/20130920152414/http://lwd.dol.state.nj.us/labor/lpa/pub/lmv/LMV_1.pdf |date=September 20, 2013 }}, [[New Jersey Department of Labor and Workforce Development]], March 15, 2011. Accessed October 6, 2013.</ref><ref name=CPH232/> The most populous municipality in Mercer County at the 2020 census was [[Hamilton Township, Mercer County, New Jersey|Hamilton Township]], with 92,297 residents,<ref name=LWD2020/> while [[Hopewell Township, Mercer County, New Jersey|Hopewell Township]] was the largest in area.<ref name=CensusArea/>

The county was formed by an act of the [[New Jersey Legislature]] on February 22, 1838, from portions of [[Burlington County, New Jersey|Burlington County]] ([[Nottingham Township, Mercer County, New Jersey|Nottingham Township]], now [[Hamilton Township, Mercer County, New Jersey|Hamilton Township]]), [[Hunterdon County, New Jersey|Hunterdon County]] ([[Ewing Township, New Jersey|Ewing Township]], [[Lawrence Township, Mercer County, New Jersey|Lawrence Township]], [[Trenton, New Jersey|Trenton]], and portions of [[Hopewell Township, Mercer County, New Jersey|Hopewell Township]]), and [[Middlesex County, New Jersey|Middlesex County]] ([[West Windsor Township, New Jersey|West Windsor Township]] and portions of [[East Windsor Township, New Jersey|East Windsor Township]]).<ref name=Story>Snyder, John P. [http://www.state.nj.us/dep/njgs/enviroed/oldpubs/bulletin67.pdf ''The Story of New Jersey's Civil Boundaries: 1606-1968''] {{webarchive|url=https://web.archive.org/web/20120605161833/http://www.state.nj.us/dep/njgs/enviroed/oldpubs/bulletin67.pdf |date=June 5, 2012 }}, Bureau of Geology and Topography; Trenton, New Jersey; 1969. p. 161. Accessed October 1, 2013.</ref> The former [[Quintipartite Deed|Keith Line]] bisects the county and is the boundary between municipalities that previously had been separated into [[West Jersey]] and [[East Jersey]].

[[Trenton–Mercer Airport]] in [[Ewing Township, New Jersey|Ewing Township]] is a [[commercial aviation|commercial]] and [[corporate aviation]] airport serving Mercer County and its surrounding vicinity. [[Princeton, New Jersey|Princeton]] is home to [[Princeton University]], one of the world’s most acclaimed [[research]] universities, and to [[Drumthwacket]], the official residence of the [[governor of New Jersey]]. Mercer County contains 12 municipalities, the fewest of any county in New Jersey, and equal to [[Hudson County, New Jersey|Hudson County]]. 

[[File:1904 US Route 1 big.JPG|thumb|upright=1.1|Trenton-New Brunswick Turnpike, the future [[U.S. Route 1 in New Jersey|U.S. Route 1]] through Mercer County, 1904]]
[[File:Princeton (6035183309).jpg|thumb|upright=1.1|Holder Tower in [[Princeton University]], one of the world's most prominent [[research]] universities<ref name=PrincetonUSNews2>{{cite magazine|url=https://www.usnews.com/best-colleges/princeton-university-2627|title=Princeton University|magazine=[[U.S. News & World Report]]|access-date=September 10, 2018}}</ref>]]

==Etymology==
The county was named for [[Continental Army]] [[Hugh Mercer|General Hugh Mercer]], who died as a result of wounds received at the [[Battle of Princeton]] on January&nbsp;3, 1777.<ref>[[Joseph Nathan Kane|Kane, Joseph Nathan]]; and Aiken, Charles Curry. [https://books.google.com/books?id=yC9vFvCuW84C&pg=PA201 ''The American Counties: Origins of County Names, Dates of Creation, and Population Data, 1950-2000''], p. 201. [[Scarecrow Press]], 2005. {{ISBN|0810850362}}. Accessed January 21, 2013.</ref> Continental Army Brigadier General [[Hugh Mercer]] served in the Continental Army during the [[Battle of Trenton]] and the Battle of Princeton in 1777. A Scotsman that fled to British North America after the failed [[Jacobite Rebellion]], he worked closely with George Washington in the American Revolution. On January 3, 1777, Washington's army was en route to Princeton, New Jersey. While leading a vanguard of 350 soldiers, Mercer's brigade encountered two British regiments and a mounted unit. A fight broke out at an orchard grove and Mercer's horse was shot from under him. Getting to his feet, he was quickly surrounded by British troops who mistook him for George Washington and ordered him to surrender. Outnumbered, he drew his saber and began an unequal contest. He was finally beaten to the ground, bayoneted repeatedly (seven times), and left for dead. Legend has it that a beaten Mercer, with a bayonet still impaled in him, did not want to leave his men and the battle and was given a place to rest on a white oak tree's trunk, and those who remained with him stood their ground. The [[Mercer Oak]], against which the dying general rested as his men continued to fight, appears on the county seal and stood for 250 years until it collapsed in 2000.<ref>[http://www.visitprincetonbattlefield.org/visit-princeton-battlefield/princeton-battlefield-state-park/mercer-oak/ Princeton Battlefield's Mercer Oak] {{webarchive|url=https://web.archive.org/web/20140121034122/http://www.visitprincetonbattlefield.org/visit-princeton-battlefield/princeton-battlefield-state-park/mercer-oak/ |date=January 21, 2014 }}, Princeton Battlefield's Clarke House Volunteers. Accessed October 6, 2013. "This white oak later became the symbol for Mercer County (named for the general), Princeton Township, the NJ Green Acres program, and other agencies. The approximately 250-year-old tree collapsed of its own weight March 3, 2000."</ref>

==History==
Founded February 22, 1838, from portions of surrounding counties, Mercer County has a historical impact that reaches back to the pivotal battles of the [[American Revolutionary War]]. On the night of December&nbsp;25–26, 1776, General [[George Washington]] led American forces [[George Washington's crossing of the Delaware River|across the Delaware River]] to attack the [[Hessian (soldier)|Hessian]] forces in the [[Battle of Trenton]] on the morning of December&nbsp;26, also known as the First Battle of Trenton. After the battle, Washington crossed back to Pennsylvania. He crossed a third time in a surprise attack on the forces of General [[Charles Cornwallis]] at the [[Battle of the Assunpink Creek]], on January&nbsp;2, 1777, also known as the Second Battle of Trenton, and at the [[Battle of Princeton]] on January&nbsp;3. The successful attacks built morale among the pro-independence colonists.<ref>[http://nj.gov/counties/mercer/about/history/revolution.html Epicenter of Revolution] {{webarchive|url=https://web.archive.org/web/20140310063242/http://nj.gov/counties/mercer/about/history/revolution.html |date=March 10, 2014 }}, Mercer County. Accessed October 6, 2013.</ref> Ewing Church Cemetery in Ewing is one of the oldest cemeteries in the area, having served the Ewing community for 300 years. It is home to the burial places of hundreds of veterans from The Revolutionary War to the Vietnam War.<ref>[https://www.memorialproperties.com/cemeteries-nj/ewing/ Ewing Church Cemetery & Mausoleum]</ref>

Since 1790, [[Trenton, New Jersey|Trenton]] has served as the state's capital, earning the county the name "the Capital County." After the Legislature relocated to Trenton from [[Perth Amboy, New Jersey|Perth Amboy]] in 1790, it purchased land for £250 and 5 shillings and constructed a new state house, designed by Philadelphia-based architect Jonathan Doane, beginning in 1792. The Doane building was covered in stucco, measured {{convert|150|by|50|ft|m}}, and housed the Senate and Assembly chambers in opposite wings. To meet the demands of the growing state, the structure was expanded several times during the 19th century. New Jersey, along with Nevada, is the only state to have its capital be located at the border with another state, as Trenton is across the Delaware River from [[Pennsylvania]]. The [[List of governors' residences in the United States|official residence]] of the [[governor of New Jersey]], known as [[Drumthwacket]], is located in [[Princeton, New Jersey|Princeton]], and is listed on both the [[U.S. National Register of Historic Places]] and the [[New Jersey Register of Historic Places]].

The county experienced rapid urbanization and population growth during the first half of the 20th century due to the growth of industrialization in places such as Trenton. Mercer County was the landing spot for a fictional [[Martian]] invasion of the United States. In 1938, in what has become one of the most famous American radio plays of all time, [[Orson Welles]] acted out his ''[[The War of the Worlds (radio)|The War of the Worlds]]'' invasion. His imaginary aliens first "landed" at what is now [[West Windsor, New Jersey|West Windsor]]. A commemorative monument is erected at [[Grovers Mill, New Jersey|Grovers Mill]] park.<ref>[http://learn.southsuburbancollege.edu/theatre/groversmill/WOTWPlaque.html "War of the Worlds Monument"] {{webarchive|url=https://web.archive.org/web/20081007215552/http://learn.southsuburbancollege.edu/theatre/groversmill/WOTWPlaque.html |date=October 7, 2008 }}, [[South Suburban College]]. Accessed October 17, 2008.</ref>

There were 27 Mercer County residents killed during the [[September 11 terrorist attacks]] in [[Lower Manhattan]]. A {{convert|10|ft|adj=on}} long steel beam weighing one ton was given to the county by the [[Port Authority of New York and New Jersey]] in March 2011 and is now displayed at [[Mercer County Park]].<ref>Staff. [http://www.nj.gov/counties/mercer/news/releases/approved/110328.html "Hughes, Officials unveil section of steel beam from Sept. 11 to be used in memorial"] {{webarchive|url=https://web.archive.org/web/20121016061859/http://www.nj.gov/counties/mercer/news/releases/approved/110328.html |date=October 16, 2012 }}, Mercer County press release dated March 28, 2011. Accessed September 11, 2011. "Mercer County Executive Brian M. Hughes was flanked by firefighters and first responders from around the County today as a section of a steel beam recovered from Ground Zero was displayed for the first time. The 10-foot, 2,108-pound piece of I-beam steel was recovered from Ground Zero during the aftermath of the September 11, 2001 attacks.... Dozens of firefighters and first responders from Mercer County worked at Ground Zero for the first 10 days after September 11, Hughes said. Mercer County was also home to 27 victims."</ref>

== Geography and climate ==
{{maplink|frame=yes|zoom=8|id=Q496886|type=shape|text=Interactive map of Mercer County, New Jersey}}
According to the [[United States Census Bureau|U.S. Census Bureau]], as of the 2020 Census, the county had a total area of {{convert|228.86|sqmi}}, of which {{convert|224.44|sqmi}} was land (98.1%) and {{convert|4.42|sqmi}} was water (1.9%).<ref name=CensusArea>[https://www2.census.gov/geo/docs/maps-data/data/gazetteer/2020_Gazetteer/2020_gaz_counties_34.txt 2020 Census Gazetteer File for Counties in New Jersey], [[United States Census Bureau]]. Accessed April 1, 2023.</ref>

The county is generally flat and low-lying on the inner coastal plain, which extends up to the [[U.S. Route 1 in New Jersey|Route 1]] corridor. Further northwest, terrain rises as it ascends the [[Piedmont Plateau]], with [[The Sourlands]] encompassing the far northwestern portion of the county. [[Baldpate Mountain (Mercer County, New Jersey)|Baldpate Mountain]], in the western part of [[Hopewell Township, Mercer County, New Jersey|Hopewell Township]], is the highest point in the county, at {{convert|480|ft}} above sea level.<ref>[http://www.peakbagger.com/list.aspx?lid=13320 New Jersey County High Points] {{webarchive|url=https://web.archive.org/web/20150518173742/http://www.peakbagger.com/list.aspx?lid=13320 |date=May 18, 2015 }}, Peakbagger.com. Accessed October 5, 2013.</ref> The lowest elevation is sea level, spread out along the shores of the tidal portions of the [[Delaware River]], [[Crosswicks Creek]] and the smaller waterways within the Trenton-Hamilton Marsh in [[Hamilton Township, Mercer County, New Jersey|Hamilton Township]] and the city of [[Trenton, New Jersey|Trenton]].

=== Climate ===
Most of Mercer has a hot-summer [[humid continental climate]] (''Dfa'') except for the southern portion of the county near and including Trenton where a [[humid subtropical climate]] (''Cfa'') exists. The [[hardiness zone]]s are 6b and 7a.

{{Trenton, New Jersey weatherbox}}
{{Weather box	
| width = auto	
| single line = Y	
| location = Lawrence, Mercer County (40.2833, -74.7015), Elevation {{convert|62|ft|m|0|abbr=on}}, 1991–2020 normals, extremes 1981–2022	
| Jan record high F  =	71.6
| Feb record high F  =	77.6
| Mar record high F  =	88.2
| Apr record high F  =	95.4
| May record high F  =	95.6
| Jun record high F  =	98.3
| Jul record high F  =	102.9
| Aug record high F  =	100.8
| Sep record high F  =	97.6
| Oct record high F  =	93.8
| Nov record high F  =	80.8
| Dec record high F  =	75.4
| year record high F =	102.9
| Jan high F  =   	40.4
| Feb high F  =   	43.0
| Mar high F  =   	50.8
| Apr high F  =   	63.2
| May high F  =   	72.7
| Jun high F  =   	81.9
| Jul high F  =   	86.5
| Aug high F  =   	84.8
| Sep high F  =   	78.2
| Oct high F  =   	66.3
| Nov high F  =   	55.5
| Dec high F  =   	45.4
| year high F =   	64.2
| Jan low F  =   	23.7
| Feb low F  =   	25.2
| Mar low F  =   	32.1
| Apr low F  =   	42.0
| May low F  =   	51.6
| Jun low F  =   	60.7
| Jul low F  =   	66.1
| Aug low F  =   	64.3
| Sep low F  =   	57.3
| Oct low F  =   	45.6
| Nov low F  =   	35.8
| Dec low F  =   	28.9
| year low F =   	44.5
| Jan record low F  =	-9.9
| Feb record low F  =	-2.0
| Mar record low F  =	4.9
| Apr record low F  =	17.9
| May record low F  =	32.6
| Jun record low F  =	41.8
| Jul record low F  =	48.0
| Aug record low F  =	42.2
| Sep record low F  =	36.4
| Oct record low F  =	24.7
| Nov record low F  =	10.8
| Dec record low F  =	0.0
| year record low F =	-9.9
| precipitation colour = green	
| Jan precipitation inch  =   	3.56
| Feb precipitation inch  =   	2.76
| Mar precipitation inch  =   	4.26
| Apr precipitation inch  =   	3.68
| May precipitation inch  =   	4.04
| Jun precipitation inch  =   	4.48
| Jul precipitation inch  =   	4.94
| Aug precipitation inch  =   	4.44
| Sep precipitation inch  =   	4.18
| Oct precipitation inch  =   	4.12
| Nov precipitation inch  =   	3.32
| Dec precipitation inch  =   	4.37
| year precipitation inch =   	48.15
| Jan dew point F =	21.8
| Feb dew point F =	22.5
| Mar dew point F =	28.0
| Apr dew point F =	37.5
| May dew point F =	49.2
| Jun dew point F =	59.4
| Jul dew point F =	64.4
| Aug dew point F =	63.6
| Sep dew point F =	57.7
| Oct dew point F =	46.1
| Nov dew point F =	35.1
| Dec dew point F =	27.5
| year dew point F =	42.8
| source = PRISM<ref name=PRISM>{{cite web |url=http://prism.oregonstate.edu/explorer/|title=PRISM|access-date=June 24, 2023}}</ref>}}

===Ecology===
According to the [[A. W. Kuchler]] U.S. [[potential natural vegetation]] types, most of Mercer County would have a dominant vegetation type of Appalachian [[Oak]] (''104'') with a dominant vegetation form of Eastern [[Hardwood]] Forest (''25'') with a dominant section of Northeastern Oak/Pine (''110'') Southern Mixed Forest (''26'') in the far east near Hightstown.<ref name="Conservation Biology Institute">[https://databasin.org/datasets/1c7a301c8e6843f2b4fe63fdb3a9fe39 U.S. Potential Natural Vegetation, Original Kuchler Types, v2.0 (Spatially Adjusted to Correct Geometric Distortions)], Data Basin, Accessed June 24, 2023.</ref>

==Demographics==
{{US Census population
|1840= 21502
|1850= 27992
|1860= 37419
|1870= 46386
|1880= 58061
|1890= 79978
|1900= 95365
|1910=125657
|1920=159881
|1930=187143
|1940=197318
|1950=229781
|1960=266392
|1970=304116
|1980=307863
|1990=325824
|2000=350761
|2010=366513
|2020=387340
| estyear=2024
| estimate=392138
| estref=<ref name=Census2020/><ref name=PopEst>[https://www2.census.gov/programs-surveys/popest/tables/2020-2024/counties/totals/co-est2024-pop-34.xlsx Annual Estimates of the Resident Population for Counties in New Jersey: April 1, 2020 to July 1, 2024], [[United States Census Bureau]], released March 2025. Accessed March 26, 2025.</ref>
|footnote=Historical sources: 1790–1990<ref>Forstall, Richard L. [https://books.google.com/books?id=sezaSI_LPA8C&pg=PA108 ''Population of states and counties of the United States: 1790 to 1990 from the Twenty-one Decennial Censuses''], pp. 108-109. [[United States Census Bureau]], March 1996. {{ISBN|9780934213486}}. Accessed October 3, 2013.</ref><br />1970-2010<ref name=CPH232>[https://www.census.gov/prod/cen2010/cph-2-32.pdf#page=32 ''New Jersey: 2010 - Population and Housing Unit Counts; 2010 Census of Population and Housing''] {{webarchive|url=https://web.archive.org/web/20130723055400/http://www.census.gov/prod/cen2010/cph-2-32.pdf |archive-url=https://web.archive.org/web/20121019110730/http://www.census.gov/prod/cen2010/cph-2-32.pdf |archive-date=October 19, 2012 |url-status=live |date=July 23, 2013 }}, p. 6, CPH-2-32. [[United States Census Bureau]], August 2012. Accessed August 29, 2016.</ref> 2010-2019<ref name=Census2010>[https://archive.today/20200212095535/http://factfinder.census.gov/bkmk/table/1.0/en/DEC/10_DP/DPDP1/0500000US34021 DP1 - Profile of General Population and Housing Characteristics: 2010 Demographic Profile Data for Mercer County, New Jersey], [[United States Census Bureau]]. Accessed March 25, 2016.</ref> 2020<ref name=Census2020>[https://www.census.gov/quickfacts/mercercountynewjersey QuickFacts Mercer County, New Jersey], [[United States Census Bureau]]. Accessed March 26, 2025.</ref><ref name=LWD2020>[https://www.nj.gov/labor/labormarketinformation/assets/PDFs/census/2020/2020%20pl94%20Tables/2020_Mun/MCD%200_All.pdf Total Population: Census 2010 - Census 2020 New Jersey Municipalities], [[New Jersey Department of Labor and Workforce Development]]. Accessed December 1, 2022.</ref>
}}

===2020 census===
As of the [[2020 United States census]], Mercer County has a population of 387,340, making it the 12th most populous county in the state. The racial makeup of the county is quite diverse with 62.3% of the population identifying as white (and 46.7% as non-Hispanic whites), 21.6% of the population being black/African American, and 12.6% of the county's population identifying as Asian. 19.4% of Mercer County is Hispanic/Latino, 0.9% of the population is American Native/Alaskan Native/Native Hawaiian/Pacific Islander, and 2.6% identify as two or more races.<ref name=Census2020/>

5.4% of Mercer County is under the age of 5, while 21.2% are under the age of 18, and 16.0% are over the age of 65. The female population of the county stands at 50.8%, which is in line with the state as a whole.<ref name=Census2020/>

There are 150,657 housing units in Mercer County, with 63.5% of them being owned by the occupiers. There are 131,440 households with an average of 2.67 persons per household.<ref name=Census2020/>

===2010 census===
The [[2010 United States census]] counted 366,513 people, 133,155 households, and 89,480 families in the county. The [[population density]] was 1,632.2 per square mile (630.2/km<sup>2</sup>). There were 143,169 housing units at an average density of 637.6 per square mile (246.2/km<sup>2</sup>). The racial makeup was 61.39% (225,011) [[White (U.S. census)|White]], 20.28% (74,318) [[Black (U.S. census)|Black or African American]], 0.33% (1,194) [[Native American (U.S. census)|Native American]], 8.94% (32,752) [[Asian (U.S. census)|Asian]], 0.08% (295) [[Pacific Islander (U.S. census)|Pacific Islander]], 6.24% (22,856) from [[Race and ethnicity in the United States census#Race|other races]], and 2.75% (10,087) from two or more races. [[Hispanic (U.S. census)|Hispanic or Latino]] of any race were 15.09% (55,318) of the population.<ref name=Census2010/> 

Of the 133,155 households, 31.4% had children under the age of 18; 48.2% were married couples living together; 14.2% had a female householder with no husband present and 32.8% were non-families. Of all households, 26.9% were made up of individuals and 10.1% had someone living alone who was 65 years of age or older. The average household size was 2.61 and the average family size was 3.16.<ref name=Census2010/> 

22.6% of the population were under the age of 18, 10.9% from 18 to 24, 26.9% from 25 to 44, 26.9% from 45 to 64, and 12.6% who were 65 years of age or older. The median age was 37.8 years. For every 100 females, the population had 95.5 males. For every 100 females ages 18 and older there were 93 males.<ref name=Census2010/>

==Economy==
Based on data from the [[Bureau of Economic Analysis]], the county had a [[gross domestic product]] of $36.0&nbsp;billion in 2021, ranked seventh in the state and a 6.7% increase from the prior year.<ref>[https://www.bea.gov/sites/default/files/2022-12/lagdp1222.pdf ''Gross Domestic Product by County, 2021''], [[Bureau of Economic Analysis]], released December 8, 2022. Accessed July 17, 2023.</ref>

In 2015, the county had a [[Per capita personal income in the United States|per capita personal income]] of $63,720, the sixth-highest in New Jersey, and ranked 121st of 3,113 counties in the United States.<ref>[https://lwd.dol.state.nj.us/labor/lpa/industry/incpov/highcnty.xls 250 Highest Per Capita Personal Incomes available for 3113 counties in the United States: 2015], [[New Jersey Department of Labor and Workforce Development]]. Accessed October 24, 2017.</ref><ref>[https://www.bea.gov/newsreleases/regional/lapi/2016/pdf/lapi1116.pdf Local Area Personal Income: 2015] {{webarchive|url=https://web.archive.org/web/20171015182249/https://www.bea.gov/newsreleases/regional/lapi/2016/pdf/lapi1116.pdf |date=October 15, 2017 }}, [[Bureau of Economic Analysis]]. Accessed October 24, 2017.</ref> Mercer County stands among the [[highest-income counties in the United States]], with the [[Bureau of Economic Analysis]] having ranked the county as having the 78th-highest [[per capita income]] of all 3,113 counties in the United States (and the sixth-highest in New Jersey) as of 2009.<ref>[https://www.bea.gov/regional/reis/pcpihigh.cfm 250 Highest Per Capita Personal Incomes of the 3113 Counties in the United States, 2009] {{webarchive|url=https://web.archive.org/web/20171120124229/https://www.bea.gov/regional/reis/pcpihigh.cfm |date=November 20, 2017 }}, [[Bureau of Economic Analysis]]. Accessed April 9, 2012.</ref> Trenton's role as New Jersey's state capital contributes significantly to Mercer County's economic standing. 9.5% of the population is considered at or below the poverty line.

The median household income in Mercer County is $83,306. 89.6% of the population has a high school diploma, and 43.5% of the county's population has a bachelor's degree or higher, one of the highest rates in the state, as of the 2020 census.<ref name=Census2020/>

==Government==
===County government===
[[File:2014-08-30 11 07 51 View of Mercer County Court House in Trenton, New Jersey from the east.JPG|thumb|upright=1.1|[[Mercer County Courthouse (New Jersey)|Mercer County Courthouse]] in Trenton]]
[[File:Drumthwacket1.jpg|thumb|upright=1.1|[[Drumthwacket]], the official residence of the [[Governor of New Jersey]], is located in [[Princeton, New Jersey|Princeton]] and is listed on both the [[U.S. National Register of Historic Places]] and the [[New Jersey Register of Historic Places]].]]
Mercer County has a [[county executive]] form of government, in which the Mercer County Executive performs executive functions, administering the operation of the county, and a Board of County Commissioners acts in a legislative capacity.<ref>Rinde, Meir. [http://www.njspotlight.com/stories/15/10/26/explainer-what-s-a-freeholder-understanding-nj-s-complex-government-system/ "Explainer: What's a Freeholder? NJ's Unusual County Government System"] {{webarchive|url=https://web.archive.org/web/20151028133736/http://www.njspotlight.com/stories/15/10/26/explainer-what-s-a-freeholder-understanding-nj-s-complex-government-system/ |date=October 28, 2015 }}, NJ Spotlight, October 27, 2015. Accessed October 26, 2017. "Five counties &ndash; Atlantic, Bergen, Essex, Hudson, and Mercer &ndash; opted for popularly elected county executives in addition to freeholder boards."</ref><ref>Crespolini, Russ. [https://patch.com/new-jersey/longvalley/freeholder-title-abolished-new-jersey "'Freeholder' Title Abolished In New Jersey"], Long Valley, NJ Patch. August 21, 2020. Accessed December 25, 2022.</ref><ref>Brunetti, Michelle. [https://pressofatlanticcity.com/news/murphy-signs-bill-into-law-to-change-freeholder-title-to-commissioner/article_dfee2290-4c09-5a93-9c0e-6d3407cc2a7c.html "Murphy signs bill into law to change 'freeholder' title to 'commissioner'"], ''[[Press of Atlantic City]]'', August 21, 2020. Accessed December 25, 2022.</ref> The county executive is directly elected to a four-year term of office. The seven-member [[Board of County Commissioners (New Jersey)|Board of County Commissioners]], previously known as the Board of Chosen Freeholders, is elected at-large to serve three-year staggered terms of office on a staggered basis, with either two or three seats up for election each year. The Board is led by a Commissioner Chair and vice-chair, selected from among its members at an annual reorganization meeting held in January. The Commissioner Board establishes policy and provides a check on the powers of the County Executive. The Board approves all county contracts and gives advice and consent to the County Executive's appointments of department heads, and appointments to boards and commissions. The Commissioner Board votes to approve the budget prepared by the Executive after review and modifications are made.<ref>[http://www.mercercounty.org/government/board-of-freeholders-/about/what-is-a-freeholder What is a Freeholder?] {{webarchive|url=https://web.archive.org/web/20171022193351/http://www.mercercounty.org/government/board-of-freeholders-/about/what-is-a-freeholder |date=October 22, 2017 }}, Mercer County, New Jersey. Accessed October 21, 2017.</ref> In 2016, freeholders were paid $29,763 and the freeholder director was paid an annual salary of $31,763.<ref>Gallo Jr., Bill. [http://www.nj.com/news/index.ssf/2016/03/how_much_your_county_freeholders_others_in_nj_earn.html "Which N.J. county freeholders are paid the most?"] {{webarchive|url=https://web.archive.org/web/20171026113548/http://www.nj.com/news/index.ssf/2016/03/how_much_your_county_freeholders_others_in_nj_earn.html |date=October 26, 2017 }}, [[NJ.com]], March 11, 2016. Accessed October 25, 2017. "Freeholder chairman: $31,763; Other freeholders: $29,763"</ref> That year, the county executive was paid $164,090 per year.<ref>Shea, Kevin. [http://www.nj.com/mercer/index.ssf/2016/02/see_how_much_mercer_county_directors_will_be_paid.html "See the proposed salaries for Mercer County directors"] {{webarchive|url=https://web.archive.org/web/20171029071356/http://www.nj.com/mercer/index.ssf/2016/02/see_how_much_mercer_county_directors_will_be_paid.html |date=October 29, 2017 }}, [[NJ.com]], February 11, 2016. Accessed October 28, 2017. "County Executive, $164,090"</ref>

{{As of|2025}}, the [[Mercer County Executive]] is [[Daniel R. Benson]] ([[Democratic Party (New Jersey)|D]], [[Hamilton Township, Mercer County, New Jersey|Hamilton Township]]) whose term of office ends December 31, 2027.<ref>[https://www.mercercounty.org/government/county-executive/meet-the-county-executive Meet the County Executive], Mercer County. Accessed January 20, 2024. "Message from County Executive Dan Benson"</ref> Mercer County's Commissioners are (with terms for chair and vice chair ending every December 31):

{| class="wikitable sortable"
|-
! Commissioner 
! Party, Residence, Term 
|-
| Chair John A. Cimino 
| D, [[Hamilton Township, Mercer County, New Jersey|Hamilton Township]], 2026<ref>[https://www.mercercounty.org/government/board-of-county-commissioners/meet-the-commissioners/john-a-cimino John A. Cimino], Mercer County. Accessed March 1, 2023.</ref>  
|- 
| Vice Chair Kristin L. McLaughlin 
| D, [[Hopewell Township, Mercer County, New Jersey|Hopewell Township]], 2027<ref>[https://www.mercercounty.org/government/board-of-county-commissioners/meet-the-commissioners/ann-m-cannon Kristin L. McLaughlin], Mercer County. Accessed March 1, 2023.</ref> 
|-
| Samuel T. Frisby Sr. 
| D, [[Trenton, New Jersey|Trenton]], 2027<ref>[https://www.mercercounty.org/government/board-of-county-commissioners/meet-the-commissioners/samuel-t-frisby-sr-chairman Samuel T. Frisby Sr.], Mercer County. Accessed March 1, 2023.</ref> 
|-
| Cathleen M. Lewis 
| D, [[Lawrence Township, Mercer County, New Jersey|Lawrence Township]], 2025<ref>[https://www.mercercounty.org/government/board-of-county-commissioners/meet-the-commissioners/andrew-koontz Cathleen M. Lewis], Mercer County. Accessed March 1, 2023.</ref> 
|-
| Nina D. Melker 
| D, Hamilton Township, 2025<ref>[https://www.mercercounty.org/government/board-of-county-commissioners/meet-the-commissioners/nina-d-melker-vice-chair Nina D. Melker], Mercer County. Accessed March 1, 2023.</ref> 
|-
| Terrance Stokes 
| D, Ewing Township, 2027<ref>[https://www.mercercounty.org/government/board-of-county-commissioners/meet-the-commissioners/pasquale-pat-colavita-jr Terrance Stokes], Mercer County. Accessed March 1, 2023.</ref><ref>[https://www.mercercounty.org/government/board-of-county-commissioners/meet-the-commissioners/ Meet the Commissioners], Mercer County. Accessed March 1, 2023.</ref><ref>[https://www.mercercounty.org/home/showpublisheddocument/22988/637819969746830000 2022 County Data Sheet], Mercer County. Accessed March 1, 2023.</ref>
|-
| Lucylle R. S. Walter 
| D, [[Ewing Township, New Jersey|Ewing Township]], 2026<ref>[https://www.mercercounty.org/government/board-of-county-commissioners/meet-the-commissioners/lucylle-r-s-walter Lucylle R. S. Walter], Mercer County. Accessed March 1, 2023.</ref>
|} 

Pursuant to Article VII Section II of the [[New Jersey State Constitution]], each county in New Jersey is required to have three elected administrative officials known as "constitutional officers." These officers are the [[County Clerk]] and [[Probate Court|County Surrogate]] (both elected for five-year terms of office) and the [[Sheriff|County Sheriff]] (elected for a three-year term).<ref>[https://www.nj.gov/state/archives/docconst47.html#page16 New Jersey State Constitution (1947), Article VII, Section II, Paragraph 2] {{webarchive|url=https://web.archive.org/web/20141101123505/http://www.nj.gov/state/archives/docconst47.html |date=November 1, 2014 }}, [[New Jersey Department of State]]. Accessed December 25, 2022.</ref> Mercer County's constitutional officers are:

{| class="wikitable sortable"
|-
! Title
! Representative
|-
| County Clerk
| Paula Sollami-Covello (D, Lawrence Township, 2025),<ref>[https://www.mercercounty.org/government/county-clerk/meet-the-clerk Meet the Clerk], Mercer County. Accessed March 1, 2023.</ref><ref>[https://coanj.com/member-list/clerks/ Members List: Clerks], Constitutional Officers Association of New Jersey. Accessed March 1, 2023.</ref> 
|-
| Sheriff
| John A. Kemler (D, Hamilton Township, 2026)<ref>[https://www.mercercounty.org/government/sheriff/meet-the-sheriff Meet the Sheriff], Mercer County. Accessed March 1, 2023.</ref><ref>[https://coanj.com/member-list/sheriffs/ Members List: Sheriffs], Constitutional Officers Association of New Jersey. Accessed March 1, 2023.</ref> 
|-
| Surrogate
|  Diane Gerofsky (D, Lawrence Township, 2026).<ref>[https://www.mercercounty.org/government/county-surrogate/meet-the-surrogate Meet the Surrogate], Mercer County. Accessed March 1, 2023.</ref><ref>[https://coanj.com/member-list/surrogates/ Members List: Surrogates], Constitutional Officers Association of New Jersey. Accessed March 1, 2023.</ref><ref name=TemplateOfficials>[http://www.mercercounty.org/home/showdocument?id=9138 Elected Officials for Mercer County], Mercer County. Accessed March 1, 2023.</ref>
|}

No Republican has won countywide office since 2000. Law enforcement on the county level is provided by the Mercer County Sheriff's Office and the Mercer County Prosecutor's Office. The Mercer County Prosecutor is Angelo J. Onofri of Hamilton Township, who took office in December 2016 after being nominated by [[Governor of New Jersey]] [[Chris Christie]] and being confirmed by the [[New Jersey Senate]].<ref>[http://mercercountyprosecutor.com/the-prosecutor/ The Prosecutor - Angelo J. Onofri, Prosecutor] {{webarchive|url=https://web.archive.org/web/20171026111113/http://mercercountyprosecutor.com/the-prosecutor/ |date=October 26, 2017 }}, Mercer County's Prosecutor Office. Accessed October 25, 2017. "Angelo J. Onofri was sworn in as Mercer County prosecutor on December 28, 2016, after being appointed by Governor Chris Christie and unanimously confirmed by the New Jersey Senate. He had been serving as acting prosecutor since March 1, 2015."</ref><ref>[http://www.state.nj.us/governor/news/news/552016/approved/20161014a.html "Governor Chris Christie Files Nominations"] {{webarchive|url=https://web.archive.org/web/20170108164012/http://www.state.nj.us/governor/news/news/552016/approved/20161014a.html |date=January 8, 2017 }}, [[Governor of New Jersey]] [[Chris Christie]], press release dated October 14, 2016. "MERCER COUNTY PROSECUTOR - Nominate for appointment Angelo Onofri (Hamilton, Mercer)"</ref> Mercer County constitutes Vicinage 7 of the [[Superior Court of New Jersey]].<ref name="NJ Courts">[https://www.judiciary.state.nj.us/courts/vicinages/mercer.html Mercer Vicinage] {{webarchive|url=https://web.archive.org/web/20171002164615/http://www.judiciary.state.nj.us/courts/vicinages/mercer.html |date=October 2, 2017 }}, New Jersey Courts. Accessed October 21, 2017.</ref> The vicinage is seated at the Mercer County Criminal Courthouse, located at 400 South Warren Street in [[Trenton, New Jersey|Trenton]].<ref name = "NJ Courts" /> The vicinage has additional facilities for the Civil, Special Civil, General Equity, and Family Parts at the Mercer County Civil Courthouse, located at 175 South Broad Street, also in Trenton.<ref name = "NJ Courts" /> The Assignment Judge for Mercer County is Mary C. Jacobson.<ref name = "NJ Courts" />

=== Federal representatives ===
Portions of the [[New Jersey's 3rd congressional district|3rd]] and [[New Jersey's 12th congressional district|12th]] [[New Jersey's congressional districts|Congressional Districts]] cover the county.<ref>[https://www.njredistrictingcommission.org/documents/2021/Data2021/Plan%20Components.pdfPlan Components Report], [[New Jersey Redistricting Commission]], December 23, 2021. Accessed November 5, 2022.</ref> {{NJ Congress 03}} {{NJ Congress 12}}

=== State representatives ===
The 12 municipalities of Mercer County are covered by three legislative districts. 

{| class="wikitable"
|+
!District
!Senator<ref name=":0">{{Cite web|title=New Jersey Legislature - Legislative Roster|url=https://www.njleg.state.nj.us/members/roster.asp|access-date=June 15, 2021|website=www.njleg.state.nj.us}}</ref>
!Assembly<ref name=":0" />
!Municipalities
|-
|[[New Jersey's 14th legislative district|14th]]
|[[Linda R. Greenstein]] [[Democratic Party (New Jersey)|(D)]]
|[[Wayne DeAngelo]] (D)
[[Tennille McCoy]] (D)
|[[East Windsor Township, New Jersey|East Windsor Township]], [[Hamilton Township, Mercer County, New Jersey|Hamilton Township]], [[Hightstown, New Jersey|Hightstown Borough]] and [[Robbinsville Township, New Jersey|Robbinsville Township]]
The remainder of the district includes portions of [[Middlesex County, New Jersey|Middlesex County]].
|-
|[[New Jersey's 15th legislative district|15th]]
|[[Shirley Turner]] (D)
|[[Verlina Reynolds-Jackson]] (D)
[[Anthony Verrelli]] (D)
|[[Ewing Township, New Jersey|Ewing Township]], [[Hopewell, New Jersey|Hopewell Borough]], [[Hopewell Township, Mercer County, New Jersey|Hopewell Township]], [[Lawrence Township, Mercer County, New Jersey|Lawrence Township]],[[Pennington, New Jersey|Pennington Borough]], [[Trenton, New Jersey|Trenton]] and [[West Windsor Township, New Jersey|West Windsor Township]]
The remainder of the district includes portions of [[Hunterdon County, New Jersey|Hunterdon County]].
|-
|[[New Jersey's 16th legislative district|16th]]
|[[Andrew Zwicker]] (D)
|[[Mitchelle Drulis]] (D)
[[Roy Freiman]] (D)
|[[Princeton, New Jersey|Princeton]] 
The remainder of the district covers portions of [[Hunterdon County, New Jersey|Hunterdon County]], [[Middlesex County, New Jersey|Middlesex County]], and [[Somerset County, New Jersey|Somerset County]].
|}

== Politics ==
Mercer County is a reliably Democratic county; it has gone for Republicans only three times (in [[1956 United States presidential election|1956]], [[1972 United States presidential election|1972]], [[1984 United States presidential election|1984]]) since [[1936 United States presidential election|1936]]. In each presidential election of the 21st century, the Democratic candidate earned at least 60% of the vote. Since the 2008 election, every municipality has voted for the Democratic candidate, and in the 2024 election, it was the 2nd most Democratic county in the state. This comes after [[Joe Biden]] won the county by 40.0% in [[2020 United States presidential election|2020]], the widest margin for anyone since [[United States presidential election|1964]]. As of October 1, 2021, there were a total of 265,703 registered voters in Mercer County, of whom 121,653 (45.8%) were registered as [[Democratic Party (New Jersey)|Democrats]], 41,701 (15.7%) were registered as [[Republican Party (New Jersey)|Republicans]] and 98,343 (37.0%) were registered as [[Unaffiliated (New Jersey)|unaffiliated]]. There were 4,006 voters (1.5%) registered to other parties.<ref>[https://www.state.nj.us/state/elections/assets/pdf/svrs-reports/2021/2021-10-voter-registration-by-county.pdf Statewide Voter Registration Summary as of October 1, 2021], [[New Jersey Department of State]]. Accessed July 28, 2022.</ref>

{{PresHead|place=Mercer County, New Jersey|source=<ref>{{cite web|url=http://uselectionatlas.org/RESULTS|title=Dave Leip's Atlas of U.S. Presidential Elections|first=David|last=Leip|website=uselectionatlas.org|access-date=April 30, 2018|url-status=live|archive-url=https://web.archive.org/web/20180323225526/https://uselectionatlas.org/RESULTS/|archive-date=March 23, 2018}}</ref>}}
<!-- PresRow should be {{PresRow|Year|Winning party|GOP vote #|Dem vote #|3rd party vote #|State}} -->
{{PresRow|2024|Democratic|52,274|107,558|3,947|New Jersey}}
{{PresRow|2020|Democratic|51,641|122,532|3,050|New Jersey}}
{{PresRow|2016|Democratic|46,193|104,775|7,090|New Jersey}}
{{PresRow|2012|Democratic|47,355|104,377|3,623|New Jersey}}
{{PresRow|2008|Democratic|50,223|107,926|2,229|New Jersey}}
{{PresRow|2004|Democratic|56,604|91,580|1,326|New Jersey}}
{{PresRow|2000|Democratic|46,670|83,256|5,633|New Jersey}}
{{PresRow|1996|Democratic|40,559|77,641|13,526|New Jersey}}
{{PresRow|1992|Democratic|50,473|71,383|23,404|New Jersey}}
{{PresRow|1988|Democratic|65,384|68,712|1,249|New Jersey}}
{{PresRow|1984|Republican|71,195|66,398|528|New Jersey}}
{{PresRow|1980|Democratic|53,450|60,888|14,244|New Jersey}}
{{PresRow|1976|Democratic|58,453|69,621|2,782|New Jersey}}
{{PresRow|1972|Republican|69,303|62,180|1,708|New Jersey}}
{{PresRow|1968|Democratic|45,354|63,218|16,957|New Jersey}}
{{PresRow|1964|Democratic|35,081|86,985|148|New Jersey}}
{{PresRow|1960|Democratic|46,924|74,166|179|New Jersey}}
{{PresRow|1956|Republican|56,029|52,684|392|New Jersey}}
{{PresRow|1952|Democratic|50,423|57,751|488|New Jersey}}
{{PresRow|1948|Democratic|37,794|49,690|1,952|New Jersey}}
{{PresRow|1944|Democratic|36,844|52,383|144|New Jersey}}
{{PresRow|1940|Democratic|37,190|50,121|222|New Jersey}}
{{PresRow|1936|Democratic|29,283|47,702|579|New Jersey}}
{{PresRow|1932|Republican|33,715|30,284|2,880|New Jersey}}
{{PresRow|1928|Republican|41,056|27,908|374|New Jersey}}
{{PresRow|1924|Republican|30,689|14,639|6,223|New Jersey}}
{{PresRow|1920|Republican|29,626|15,713|1,344|New Jersey}}
{{PresRow|1916|Republican|14,213|10,621|659|New Jersey}}
{{PresRow|1912|Democratic|5,676|7,773|7,671|New Jersey}}
{{PresRow|1908|Republican|14,941|9,288|1,100|New Jersey}}
{{PresRow|1904|Republican|14,900|8,528|1,158|New Jersey}}
{{PresRow|1900|Republican|13,878|7,861|769|New Jersey}}
{{PresRow|1896|Republican|13,847|5,970|901|New Jersey}}
|}

{{Hidden begin
|titlestyle = background:#ccccff;
|title      = Gubernatorial elections results
}}
{| class="wikitable" style="float:right; margin: 1em 1em 1em 0;"
|+ '''Gubernatorial elections results'''<ref>{{cite web|url=https://nj.gov/state/elections/election-information-results.shtml| title=NJ DOS - Division of Elections - Election Results Archive }}</ref>
|-
! Year
! [[Republican Party (United States)|Republican]]
! [[Democratic Party (United States)|Democratic]]
|-
| style="text-align:center;" {{Party shading/Democratic}}|'''[[2021 New Jersey gubernatorial election|2021]]'''
| style="text-align:center;" {{Party shading/Republican}}|34.1% ''34,617''
| style="text-align:center;" {{Party shading/Democratic}}|'''65.1%''' ''66,151''
|-
| style="text-align:center;" {{Party shading/Democratic}}|'''[[2017 New Jersey gubernatorial election|2017]]'''
| style="text-align:center;" {{Party shading/Republican}}|33.1%' ''30,645''
| style="text-align:center;" {{Party shading/Democratic}}|'''64.9%''' ''59,992''
|-
| style="text-align:center;" {{Party shading/Republican}}|'''[[2013 New Jersey gubernatorial election|2013]]'''
| style="text-align:center;" {{Party shading/Republican}}|'''51.9% ''' ''48,530''
| style="text-align:center;" {{Party shading/Democratic}}|46.3% ''43,282''
|-
| style="text-align:center;" {{Party shading/Democratic}}|'''[[2009 New Jersey gubernatorial election|2009]]'''
| style="text-align:center;" {{Party shading/Republican}}|39.3% ''39,769''
| style="text-align:center;" {{Party shading/Democratic}}|'''54.5%''' ''55,199''
|-
| style="text-align:center;" {{Party shading/Democratic}}|'''[[2005 New Jersey gubernatorial election|2005]]'''
| style="text-align:center;" {{Party shading/Republican}}|39.2% ''38,871''
| style="text-align:center;" {{Party shading/Democratic}}|'''57.1%''' ''56,592''
|-
| style="text-align:center;" {{Party shading/Democratic}}|'''[[2001 New Jersey gubernatorial election|2001]]'''
| style="text-align:center;" {{Party shading/Republican}}|33.6% ''31,705''
| style="text-align:center;" {{Party shading/Democratic}}|'''60.9%''' ''57,513''
|-
| style="text-align:center;" {{Party shading/Democratic}}|'''[[1997 New Jersey gubernatorial election|1997]]'''
| style="text-align:center;" {{Party shading/Republican}}|40.8% ''44,056''
| style="text-align:center;" {{Party shading/Democratic}}|'''50.9%''' ''54,977''
|-
| style="text-align:center;" {{Party shading/Republican}}|'''[[1993 New Jersey gubernatorial election|1993]]'''
| style="text-align:center;" {{Party shading/Republican}}|'''52.0%''' ''57,599''
| style="text-align:center;" {{Party shading/Democratic}}|45.9% ''50,840''
|-
| style="text-align:center;" {{Party shading/Democratic}}|'''[[1989 New Jersey gubernatorial election|1989]]'''
| style="text-align:center;" {{Party shading/Republican}}|30.1% ''29,987''
| style="text-align:center;" {{Party shading/Democratic}}|'''68.5% ''' ''67,962''
|-
| style="text-align:center;" {{Party shading/Republican}}|'''[[1985 New Jersey gubernatorial election|1985]]'''
| style="text-align:center;" {{Party shading/Republican}}|'''63.2% ''' ''53,562''
| style="text-align:center;" {{Party shading/Democratic}}|35.6% ''30,212''
|-
| style="text-align:center;" {{Party shading/Democratic}}|'''[[1981 New Jersey gubernatorial election|1981]]'''
| style="text-align:center;" {{Party shading/Republican}}|43.8% ''43,156''
| style="text-align:center;" {{Party shading/Democratic}}|'''54.8%''' ''53,897''
|-
| style="text-align:center;" {{Party shading/Democratic}}|'''[[1977 New Jersey gubernatorial election|1977]]'''
| style="text-align:center;" {{Party shading/Republican}}|32.9% ''32,994''
| style="text-align:center;" {{Party shading/Democratic}}|'''65.3% ''' ''65,371''
|-
| style="text-align:center;" {{Party shading/Democratic}}|'''[[1973 New Jersey gubernatorial election|1973]]'''
| style="text-align:center;" {{Party shading/Republican}}|22.3% ''20,859''
| style="text-align:center;" {{Party shading/Democratic}}|'''76.3% ''' ''71,527''
|-
|}
{{Hidden end}}

==Transportation==
[[File:Princeton X.jpg|thumb|upright=1.1|[[New Jersey Route 27|Nassau Street]] in [[Princeton, New Jersey|Princeton]]]]

===Roads and highways===
Mercer County has county routes, state routes, U.S. Routes and Interstates that all pass through. {{As of|2010}}, the county had a total of {{convert|1524.30|mi}} of roadways, of which {{convert|1216.48|mi}} were maintained by the local municipality, {{convert|175.80|mi}} by Mercer County, {{convert|118.99|mi}} by the [[New Jersey Department of Transportation]], {{convert|1.19|mi}} by the [[Delaware River Joint Toll Bridge Commission]] and {{convert|12.43|mi}} by the [[New Jersey Turnpike Authority]].<ref>[https://www.state.nj.us/transportation/refdata/sldiag/pdf/mileage_Mercer.pdf Mercer County Mileage by Municipality and Jurisdiction], [[New Jersey Department of Transportation]], March 2019. Accessed December 26, 2020.</ref>


Mercer County is served by the following major roadways:<ref>{{Cite web |title=NJDOT SLD Sheet Viewer |url=https://njsld.org/NJDOT/SLD/SheetViewer |access-date=November 26, 2023 |website=njsld.org}}</ref>

* [[U.S. Route 1 in New Jersey|U.S. Route 1]] (Which bisects the county)
* [[U.S. Route 1 Business (Trenton, New Jersey)|U.S. Route 1 Business]]
* [[New Jersey Route 27|Route 27]] (Only in [[Princeton, New Jersey|Princeton]])
* [[New Jersey Route 29|Route 29]]
* [[New Jersey Route 31|Route 31]]
* [[New Jersey Route 33|Route 33]]
* [[New Jersey Route 64|Route 64]] (A small state-maintained bridge located in [[West Windsor, New Jersey|West Windsor]])
* [[Interstate 95 in New Jersey|Interstate 95]] ([[New Jersey Turnpike]])
* [[New Jersey Route 129|Route 129]]
* [[U.S. Route 130]]
* [[New Jersey Route 133|Route 133]] (Only in [[East Windsor, New Jersey|East Windsor]])
* [[Interstate 195 (New Jersey)|Interstate 195]]
* [[U.S. Route 206]]
* [[Interstate 295 (New Jersey)|Interstate 295]]

I-295 functions as a partial ring-road around the Trenton area, while I-195 serves as an east–west expressway from Trenton to the [[Jersey Shore]]. The New Jersey Turnpike (I-95) passes through the southeastern section of the county, and serves as a major corridor to [[Delaware]], [[Washington, D.C.]] to the south, and [[New York City]] and [[New England]] towards the north. Two turnpike interchanges are located within Mercer County: Exit 7A in [[Robbinsville Township, New Jersey|Robbinsville Township]] and Exit 8 in [[East Windsor Township, New Jersey|East Windsor Township]].

Before 2018, Interstate 95 abruptly ended at the interchange with US 1 in [[Lawrence Township, Mercer County, New Jersey|Lawrence Township]], and became I-295 south. Signs directed motorists to the continuation of I-95 by using I-295 to I-195 east to the New Jersey Turnpike. This was all due in part to the cancellation of the [[Somerset Freeway]] that was supposed to go from [[Hopewell Township, Mercer County, New Jersey|Hopewell Township]] in Mercer County up to [[Franklin Township, Somerset County, New Jersey|Franklin Township]] in [[Somerset County, New Jersey|Somerset County]].<ref>Frassinelli, Mike. [http://www.nj.com/news/index.ssf/2010/09/nj_pa_officials_plan_to_close.html "N.J., Pennsylvania officials plan to close longtime gap on Route 95"] {{webarchive|url=https://web.archive.org/web/20100910090636/http://www.nj.com/news/index.ssf/2010/09/nj_pa_officials_plan_to_close.html|date=September 10, 2010}}, ''[[The Star-Ledger]]'', September 7, 2010. Accessed October 24, 2017. "Plans to run I-95 north of Trenton to Route 287 near Perth Amboy as part of the 'Somerset Freeway' were scuttled in 1980 after residents in the Princeton area feared a potential loss in property values and their small-town feel."</ref>

The section of I-95 west of the US 1 interchange in Lawrence was re-numbered as part of I-295 in March 2018, six months before a [[Pennsylvania Turnpike/Interstate 95 Interchange Project|direct interchange]] with [[Interstate 95 in Pennsylvania]] and the [[Pennsylvania Turnpike]] opened.<ref>{{cite letter|last=Nadeau|first=Gregory G.|date=May 20, 2015|title=FHWA to AASHTO I-95 Designation|recipient=Bud Wright|location=Washington, DC|publisher=Federal Highway Administration|url=http://route.transportation.org/Documents/05%2014%202015%20Cheyenne%2c%20WY%20Report/FHWA%20to%20AASHTO%20I-95.Designation.pdf|format=PDF|access-date=June 8, 2015|url-status=dead|archive-url=https://web.archive.org/web/20150609165553/http://route.transportation.org/Documents/05%2014%202015%20Cheyenne%2C%20WY%20Report/FHWA%20to%20AASHTO%20I-95.Designation.pdf|archive-date=June 9, 2015}}</ref> This planned interchange indirectly prompted another project: the New Jersey Turnpike Authority extended the 'dual-dual' configuration (inner car lanes and outer truck / bus / car lanes) to Interchange 6 in [[Mansfield Township, Burlington County, New Jersey|Mansfield Township]], [[Burlington County, New Jersey|Burlington County]] from its former end at Interchange 8A in [[Monroe Township, Middlesex County, New Jersey|Monroe Township]], [[Middlesex County, New Jersey|Middlesex County]]. This widening was completed in early November 2014.<ref>[http://www.state.nj.us/turnpike/documents/NEWS_RELEASE_Gov_Christie_Commissioner_Fox_cut_ribbon_Turnpike_Widening.pdf Gov. Christie, NJDOT Commissioner FoxPraise $2.3 Billion NJ Turnpike Infrastructure Investment Project] {{webarchive|url=https://web.archive.org/web/20141103174930/http://www.state.nj.us/turnpike/documents/NEWS_RELEASE_Gov_Christie_Commissioner_Fox_cut_ribbon_Turnpike_Widening.pdf|date=November 3, 2014}}, [[New Jersey Turnpike Authority]]. Accessed November 3, 2014. "The Widening Program created a three-lane Outer Roadway in each direction over the 25 miles between Interchange 6 in Mansfield Township, Burlington County, and Interchange 8A in Monroe Township, Middlesex County."</ref>


The county roads that traverse through are [[County Route 518 (New Jersey)|County Route 518]] (only in the Hopewells), [[County Route 524 (New Jersey)|County Route 524]], [[County Route 526 (New Jersey)|County Route 526]], [[County Route 533 (New Jersey)|County Route 533]], [[County Route 535 (New Jersey)|County Route 535]], [[County Route 539 (New Jersey)|County Route 539]], [[County Route 546 (New Jersey)|County Route 546]], [[County Route 569 (New Jersey)|County Route 569]], [[County Route 571 (New Jersey)|County Route 571]], and [[County Route 583 (New Jersey)|County Route 583]].

===Public transportation===
Mercer hosts several [[NJ Transit]] stations, including [[Trenton Transit Center|Trenton]], [[Hamilton station (NJ Transit)|Hamilton]] and [[Princeton Junction station|Princeton Junction]] on the [[Northeast Corridor Line]], as well as [[Princeton station (NJ Transit)|Princeton]] on the [[Princeton Branch]].<ref>[http://www.njtransit.com/rg/rg_servlet.srv?hdnPageAction=LineDetailsTo&selLine=NEC Northeast Corridor Line] {{webarchive|url=https://web.archive.org/web/20140712073924/http://www.njtransit.com/rg/rg_servlet.srv?hdnPageAction=LineDetailsTo&selLine=NEC |date=July 12, 2014 }}, [[NJ Transit]]. Accessed August 2, 2014.</ref> [[SEPTA]] provides rail service to [[Center City, Philadelphia|Center City]] [[Philadelphia]] from [[Trenton Transit Center|Trenton]] and [[West Trenton station|West Trenton]]. Long-distance transportation is provided by [[Amtrak]] train service along the [[Northeast Corridor]] through the [[Trenton Transit Center]].

NJ Transit's [[River Line (NJ Transit)|River Line]] connects Trenton to [[Camden, New Jersey|Camden]], with three stations in the county, all within Trenton city limits, at [[Cass Street (River Line station)|Cass Street]], [[Hamilton Avenue (River Line station)|Hamilton Avenue]] and at the Trenton Transit Center.<ref>[https://content.njtransit.com/sites/default/files/pdfs/light-rail/sf_lr_rvl_map.pdf River Line System Map], [[NJ Transit]]. Accessed November 24, 2022.</ref>

Mercer County's only [[commercial airport]], and one of three in the state, is [[Trenton–Mercer Airport]] in [[Ewing Township, New Jersey|Ewing Township]], which is served by [[Frontier Airlines]], offering nonstop service to and from points nationwide.<ref>[http://www.state.nj.us/counties/mercer/departments/airport/ Trenton Mercer Airport] {{webarchive|url=https://web.archive.org/web/20130929190306/http://www.state.nj.us/counties/mercer/departments/airport/ |date=September 29, 2013 }}, Mercer County. Accessed October 6, 2013.</ref>

==Municipalities==
[[Image:Mercer County, New Jersey Municipalities.png|thumb|upright=1.1|Index map of Mercer County municipalities (click to see index)]]
The 12 municipalities in Mercer County (with 2010 Census data for population, housing units and area) are:<ref>[https://archive.today/20200212204035/http://factfinder.census.gov/bkmk/table/1.0/en/DEC/10_SF1/GCTPH1.CY10/0500000US34021 GCT-PH1: Population, Housing Units, Area, and Density: 2010 - County &ndash; County Subdivision and Place from the 2010 Census Summary File 1 for Mercer County, New Jersey], [[United States Census Bureau]]. Accessed May 17, 2016.</ref>

{| class="wikitable sortable"
|-
! Municipality<br />(with map key)
!Map key
! Municipal<br />type
! Population
! Housing<br />Units
! Total<br />Area (sq. mi.)
! Water<br />Area (sq. mi.)
! Land<br />Area (sq. mi.)
! Pop.<br />Density (pop./sq. mi.)
! Housing<br />Density (houses/sq. mi.)
!School district
! Communities<ref>[http://www.state.nj.us/infobank/localnames.txt Locality Search] {{webarchive|url=https://web.archive.org/web/20160709092825/http://www.state.nj.us/infobank/localnames.txt |date=July 9, 2016 }}, State of [[New Jersey]]. Accessed May 11, 2015.</ref>
|-
|[[East Windsor Township, New Jersey|East Windsor]]
|6|| township || 30,045 || 10,851 || 15.74 || 0.10 || 15.65 || 1,737.6 || 693.4 
|[[East Windsor Regional School District|East Windsor]]||
[[Allens Station, New Jersey|Allens Station]], [[Eilers Corner, New Jersey|Eiler Corner]], [[Etra, New Jersey|Etra]], [[Hickory Corner, New Jersey|Hickory Corner]], [[Locust Corner, New Jersey|Locust Corner]], [[Millstone, Mercer County, New Jersey|Millstone]], [[Twin Rivers, New Jersey|Twin Rivers]] CDP (7,787)
|-
|[[Ewing Township, New Jersey|Ewing Township]] 
|11|| township || 37,264 || 13,926 || 15.60 || 0.35 || 15.25 || 2,346.9 || 913.2 
|[[Ewing Public Schools|Ewing]]|| [[Altura, New Jersey|Altura]], [[Braeburn Heights, New Jersey|Braeburn Heights]], [[Briarcrest, New Jersey|Briarcrest]], [[Briarwood, New Jersey|Briarwood]], [[The College of New Jersey]] CDP (3,701) [[Churchill Green, New Jersey|Churchill Green]], [[Ewing (unincorporated community), New Jersey|Ewing]], [[Ewing Park, New Jersey|Ewing Park]], [[Ewingville, New Jersey|Ewingville]], [[Fernwood, New Jersey|Fernwood]], [[Ferry Road Manor, New Jersey|Ferry Road Manor]], [[Fleetwood Village, New Jersey|Fleetwood Village]], [[Glendale, Mercer County, New Jersey|Glendale]], [[Green Curve Heights, New Jersey|Green Curve Heights]], [[Hampton Hills, New Jersey|Hampton Hills]], [[Heath Manor, New Jersey|Heath Manor]], [[Hickory Hill Estates, New Jersey|Hickory Hill Estates]], [[Hillwood Lakes, New Jersey|Hillwood Lakes]], [[Hillwood Manor, New Jersey|Hillwood Manor]], [[Mountainview, Mercer County, New Jersey|Mountainview]], [[Parkway Village, New Jersey|Parkway Village]], [[Prospect Heights, New Jersey|Prospect Heights]], [[Prospect Park, Mercer County, New Jersey|Prospect Park]], [[Scudders Falls, New Jersey|Scudders Falls]], [[Shabakunk Hills, New Jersey|Shabakunk Hills]], [[Sherbrooke Manor, New Jersey|Sherbrooke Manor]], [[Somerset, Mercer County, New Jersey|Somerset]], [[Spring Meadows, New Jersey|Spring Meadows]], [[Village on the Green, New Jersey|Village on the Green]], [[Weber Park, New Jersey|Weber Park]], [[West Trenton, New Jersey|West Trenton]], [[Wilburtha, New Jersey|Wilburtha]], [[Wynnewood Manor, New Jersey|Wynnewood Manor]]
|-
|[[Hamilton Township, Mercer County, New Jersey|Hamilton Township]] 
|8|| township || 92,297 || 36,170 || 40.39 || 0.90 || 39.49 || 2,240.2 || 915.9 
|[[Hamilton Township School District|Hamilton Township]]|| [[Briar Manor, New Jersey|Briar Manor]], [[Broad Street Park, New Jersey|Broad Street Park]], [[Chewalla Park, New Jersey|Chewalla Park]], [[Creston, New Jersey|Creston]], [[Deutzville, New Jersey|Deutzville]], [[Duck Island, New Jersey|Duck Island]], [[East Trenton Heights, New Jersey|East Trenton Heights]], [[Edgebrook, Mercer County, New Jersey|Edgebrook]], [[Extonville, New Jersey|Extonville]], [[Golden Crest, New Jersey|Golden Crest]], [[Groveville, New Jersey|Groveville]] CDP (3,106), [[Haines Corner, Mercer County, New Jersey|Haines Corner]], [[Hamilton Square, New Jersey|Hamilton Square]] CDP (12,679), [[Hutchinson Mills, New Jersey|Hutchinson Mills]], [[Lakeside Park, New Jersey|Lakeside Park]], [[Maple Shade, Mercer County, New Jersey|Maple Shade]], [[Mercerville, New Jersey|Mercerville]] CDP (9,791), [[North Crosswicks, New Jersey|North Crosswicks]], [[Nottingham, New Jersey|Nottingham]], [[Pond Run, New Jersey|Pond Run]], [[Quaker Bridge, Mercer County, New Jersey|Quaker Bridge]], [[Quaker Gardens, New Jersey|Quaker Gardens]], [[Rosemont, Mercer County, New Jersey|Rosemont]], [[The Orchards, New Jersey|The Orchards]], [[Trenton Gardens, New Jersey|Trenton Gardens]], [[Warner Village, New Jersey|Warner Village]], [[White Horse, New Jersey|White Horse]] CDP (9,494), [[Yardville, New Jersey|Yardville]] CDP (7,186), [[Yardville Heights, New Jersey|Yardville Heights]] CDP (6,965)
|-
|[[Hightstown, New Jersey|Hightstown]] 
|5|| borough || 5,900 || 2,108 || 1.24 || 0.03 || 1.21 || 4,536.0 || 1,740.4 
|[[East Windsor Regional School District|East Windsor]]||
|-
|[[Hopewell, New Jersey|Hopewell Borough]]
|1|| borough || 1,918 || 817 || 0.70 || 0.00 || 0.70 || 2,735.2 || 1,162.7 
|[[Hopewell Valley Regional School District|Hopewell Valley]]||
|-
|[[Hopewell Township, Mercer County, New Jersey|Hopewell Township]] 
|12|| township || 17,491 || 6,551 || 58.91 || 0.88 || 58.03 || 298.2 || 112.9 
|[[Hopewell Valley Regional School District|Hopewell Valley]]|| [[Akers Corner, New Jersey|Akers Corner]], [[Baldwins Corner, New Jersey|Baldwins Corner]], [[Bear Tavern, New Jersey|Bear Tavern]], [[Centerville, Mercer County, New Jersey|Centerville]], [[Coopers Corner, New Jersey|Coopers Corner]], [[Glenmoore, New Jersey|Glenmoore]], [[Harbourton, New Jersey|Harbourton]], [[Harts Corner, New Jersey|Harts Corner]], [[Marshalls Corner, New Jersey|Marshalls Corner]], [[Moore, New Jersey|Moore]], [[Mount Rose, New Jersey|Mount Rose]], [[Pleasant Valley, Mercer County, New Jersey|Pleasant Valley]], [[Stoutsburg, New Jersey|Stoutsburg]], [[Titusville, New Jersey|Titusville]] CDP (633), [[Washington Crossing, New Jersey|Washington Crossing]] CDP (371), [[Woodsville, New Jersey|Woodsville]]
|-
|[[Lawrence Township, Mercer County, New Jersey|Lawrence Township]] 
|10|| township || 33,077 || 13,239 || 22.06 || 0.25 || 21.81 || 1,534.8 || 607.1 
|[[Lawrence Township Public Schools|Lawrence Township]]|| [[Bakersville, Mercer County, New Jersey|Bakersville]], [[Clarksville, Mercer County, New Jersey|Clarksville]], [[Colonial Lakelands, New Jersey|Colonial Lakelands]], [[Coxs Corner, Mercer County, New Jersey|Coxs Corner]], [[Eldridge Park, New Jersey|Eldridge Park]], [[Franklin Corner, New Jersey|Franklin Corner]], [[Harneys Corner, New Jersey|Harneys Corner]], [[Lawrence Station, New Jersey|Lawrence Station]], [[Lawrenceville, New Jersey|Lawrenceville]] CDP (3,751), [[Lewisville, New Jersey|Lewisville]], [[Port Mercer, New Jersey|Port Mercer]], [[Princessville, New Jersey|Princessville]], [[Quaker Bridge, Mercer County, New Jersey|Quaker Bridge]], [[Rosedale, Mercer County, New Jersey|Rosedale]], [[Slackwood, New Jersey|Slackwood]], [[Sturwood Hamlet, New Jersey|Sturwood Hamlet]]
|-
|[[Pennington, New Jersey|Pennington]] 
|2|| borough || 2,802 || 1,083 || 0.96 || 0.00 || 0.96 || 2,703.9 || 1,132.8 
|[[Hopewell Valley Regional School District|Hopewell Valley]]||
|-
|[[Princeton, New Jersey|Princeton]]{{#tag:ref|[[Princeton Township, New Jersey|Princeton Township]] and [[Borough of Princeton, New Jersey|Princeton Borough]] merged on January 1, 2013. The data is tabulated from the sum of the two municipalities' 2010 populations and areas. Though it has a borough form of government, the municipality type is classified by the state government as "other."<ref name=PrincetonType>{{cite news |url=http://planetprinceton.com/2012/10/01/merged-municipality-will-be-called-princeton-new-jersey/ |date=October 1, 2012 |title=Merged Municipality Will Be Called Princeton, New Jersey |publisher=Planet Princeton |access-date=January 2, 2013 |author=Knapp, Krystal |url-status=live |archive-url=https://web.archive.org/web/20121127072215/http://planetprinceton.com/2012/10/01/merged-municipality-will-be-called-princeton-new-jersey/ |archive-date=November 27, 2012 }}</ref>|group=note}} 
|3|| borough || 30,681 || 10,302 || 18.36 || 0.43 || 17.93 || 1,593.53 || 574.6 
|[[Princeton Public Schools|Princeton]]|| [[Cedar Grove, Mercer County, New Jersey|Cedar Grove]], [[Port Mercer, New Jersey|Port Mercer]], [[Princeton North, New Jersey|Princeton North]]

|-
|[[Robbinsville Township, New Jersey|Robbinsville Township]] 
|7|| township || 15,476 || 5,277 || 20.49 || 0.18 || 20.32 || 671.5 || 259.7 
|[[Robbinsville Public School District|Robbinsville]]|| Known as Washington Township until November 2007<br />[[Allens Station, New Jersey|Allens Station]], [[Carsons Mills, New Jersey|Carsons Mills]], [[Hillside Terrace, New Jersey|Hillside Terrace]], [[Meadows Terrace, New Jersey|Meadows Terrace]], [[New Canton, New Jersey|New Canton]], [[New Sharon, New Jersey|New Sharon]], [[Pages Corners, New Jersey|Pages Corners]], [[Robbinsville Center, New Jersey|Robbinsville Center]] CDP (3,164), [[Windsor, New Jersey|Windsor]] CDP (330)
|-
|[[Trenton, New Jersey|Trenton]] 
|4|| city || 90,871 || 33,035 || 8.16 || 0.51 || 7.65 || 11,101.9 || 4,319.2 
|[[Trenton Public Schools|Trenton]]|| [[Battle Monument, Trenton, New Jersey|Battle Monument]], [[Berkeley Square, Trenton, New Jersey|Berkeley Square]], [[Cadwalader Heights, Trenton, New Jersey|Cadwalader Heights]], [[Central West, Trenton, New Jersey|Central West]], [[Chambersburg, Trenton, New Jersey|Chambersburg]], [[Chestnut Park, Trenton, New Jersey|Chestnut Park]], [[Coalport/North Clinton, Trenton, New Jersey|Coalport/North Clinton]], [[Downtown Trenton, New Jersey|Downtown Trenton]], [[Duck Island, New Jersey|Duck Island]], [[East Trenton, New Jersey|East Trenton]], [[Ewing/Carroll, Trenton, New Jersey|Ewing/Carroll]], [[Fisher/Richey/Perdicaris, Trenton, New Jersey|Fisher/Richey/Perdicaris]], [[Franklin Park, Trenton, New Jersey|Franklin Park]], [[Glen Afton, Trenton, New Jersey|Glen Afton]], [[Greenwood/Hamilton, Trenton, New Jersey|Greenwood/Hamilton]], [[Hanover/Academy, Trenton, New Jersey|Hanover/Academy]], [[Hillcrest, Trenton, New Jersey|Hillcrest]], [[Hiltonia, Trenton, New Jersey|Hiltonia]], [[Lamberton, New Jersey|Lamberton]], [[North 25, Trenton, New Jersey|North 25]], [[North Trenton, New Jersey|North Trenton]], [[Parkside, Trenton, New Jersey|Parkside]], [[Pennington/Prospect, Trenton, New Jersey|Pennington/Prospect]], [[South Trenton, New Jersey|South Trenton]], [[Stuyvesant/Prospect, Trenton, New Jersey|Stuyvesant/Prospect]], [[The Island, Trenton, New Jersey|The Island]], [[Top Road, Trenton, New Jersey|Top Road]], [[Villa Park, Trenton, New Jersey|Villa Park]], [[West End, Trenton, New Jersey|West End]], [[Wilbur, Trenton, New Jersey|Wilbur]]
|-
|[[West Windsor Township, New Jersey|West Windsor]]
|9|| township || 29,518 || 9,810 || 26.27 || 0.71 || 25.56 || 1,062.6 || 383.7 
|[[West Windsor-Plainsboro Regional School District|West Windsor-Plainsboro]]||
[[Berrien City, New Jersey|Berrien City]], [[Clarksville, Mercer County, New Jersey|Clarksville]], [[Dutch Neck, Mercer County, New Jersey|Dutch Neck]], [[Edinburg, New Jersey|Edinburg]], [[Edinburg Park, New Jersey|Edinburg Park]], [[Golf View Manor, New Jersey|Golf View Manor]], [[Grover's Mill, New Jersey|Grover's Mill]], [[Old Mill Farms, New Jersey|Old Mill Farms]], [[Penns Neck, New Jersey|Penns Neck]], [[Port Mercer, New Jersey|Port Mercer]], [[Post Corner, New Jersey|Post Corner]], [[Princeton Colonial Park, New Jersey|Princeton Colonial Park]], [[Princeton Estates, New Jersey|Princeton Estates]], [[Princeton Ivy East, New Jersey|Princeton Ivy East]], [[Princeton Junction, New Jersey|Princeton Junction]] CDP (2,475), [[Sherbrook Estates, New Jersey|Sherbrook Estates]]
|-
|Mercer County 
| || county || 387,340 || 143,169 || 228.89 || 4.33 || 224.56 || 1,632.2 || 637.6 
| ||
|-
|}

=== Historical Municipalities ===
*[[Nottingham Township, Mercer County, New Jersey|Nottingham Township]] (1688–1856)
*[[Princeton Township, New Jersey|Princeton Township]] (1838–2013)
*[[Borough of Princeton]] (1813–2013)
*Washington Township (renamed [[Robbinsville Township, New Jersey|Robbinsville Township]] in 2008)

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==Sports==
Mercer County has a number of large parks. The largest, [[Mercer County Park]] is the home for the US Olympic Rowing Team's training center.<ref>Bruinius, Harry. [http://www.csmonitor.com/The-Culture/2008/0717/qrowing "Know, know, know your boat; In New Jersey, locals have turned out to support the US national team with pizza, housing, handiwork – and delight."] {{webarchive|url=https://web.archive.org/web/20150611004438/http://www.csmonitor.com/The-Culture/2008/0717/qrowing |date=June 11, 2015 }}, ''[[The Christian Science Monitor]]'', July 17, 2008. Accessed October 6, 2013.</ref>

Mercer County is also the home of the [[Trenton Thunder]] baseball team, playing in the [[MLB Draft League]], and the [[Jersey Flight]] of the [[National Arena League]]. The Thunder were formerly the Double-A affiliate of the [[New York Yankees]] playing in the [[Eastern League (1938–2020)|Eastern League]] before the 2021 Minor League reorganization. The minor league hockey team, the [[Trenton Titans]], established in 1999 and operating as the ECHL affiliate of the [[NHL]]'s [[Philadelphia Flyers]] and the [[American Hockey League|AHL]]'s [[Adirondack Phantoms]], disbanded before the start of the 2013–14 season.<ref>Zedalis, Joe. [http://www.nj.com/times-sports/index.ssf/2013/05/trenton_titans_fans_still_wait.html "Trenton Titans fans still waiting for ticket refunds for canceled season"] {{webarchive|url=https://web.archive.org/web/20150220022049/http://www.nj.com/times-sports/index.ssf/2013/05/trenton_titans_fans_still_wait.html |date=February 20, 2015 }}, ''[[The Times (Trenton)|Times of Trenton]]'', May 7, 2013. Accessed January 11, 2015. "The struggling Trenton Titans ice hockey franchise has yet to return advance ticket money to fans who purchased seats for the now-canceled 2013-2014 season, leaving some people waiting for refunds of up to $2,000. The team announced April 23 that they would not be returning to the ice in October."</ref>

===Collegiate athletics===
Mercer County is also home to several college athletic programs, including two [[National Collegiate Athletic Association|NCAA]] [[NCAA Division I|DI]] schools. [[Rider University]] competes as the [[Rider Broncs]] in the [[Metro Atlantic Athletic Conference|MAAC]]. In [[collegiate wrestling|wrestling]], Rider is a member of the [[Eastern Wrestling League]]. The [[Princeton Tigers]] compete in the [[Ivy League]].

[[The College of New Jersey]] Lions compete in the [[National Collegiate Athletic Association|NCAA]] [[NCAA Division III|DIII]] as a member of the [[New Jersey Athletic Conference]] and the [[Eastern College Athletic Conference]].<ref>[http://tcnj.pages.tcnj.edu/about/ About], [[The College of New Jersey]]. Accessed January 11, 2015.</ref><ref>[http://www.ecacsports.com/inside/membership/division_III/index Membership] {{webarchive|url=https://web.archive.org/web/20151209055439/http://www.ecacsports.com/inside/membership/division_III/index |date=December 9, 2015 }}, [[Eastern College Athletic Conference]]. Accessed January 11, 2015.</ref>

[[Mercer County Community College]] competes as the Mercer Vikings as a member of the [[Garden State Athletic Conference]] and the [[National Junior College Athletic Association]].

==Education==
School districts in the county include:<ref name=NJDOE>[https://homeroom5.doe.state.nj.us/directory/district.php?source=01&county=mercer New Jersey School Directory for Mercer County], [[New Jersey Department of Education]]. Accessed August 1, 2022.</ref><ref>[https://nces.ed.gov/ccd/districtsearch/district_list.asp?Search=1&details=1&State=34&County=Mercer+County Search for Public School Districts in Mercer County, New Jersey], [[National Center for Education Statistics]]. Accessed August 1, 2022.</ref><ref>[https://www2.census.gov/geo/maps/DC2020/PL20/st34_nj/schooldistrict_maps/c34021_mercer/DC20SD_C34021.pdf 2020 Census School District Reference Map for Mercer County, NJ], [[United States Census Bureau]]. Accessed August 16, 2022.</ref><ref>[https://www2.census.gov/geo/maps/DC2020/PL20/st34_nj/schooldistrict_maps/c34021_mercer/DC20SD_C34021_SD2MS.txt 2020 Census School District Reference List for Mercer County, NJ], [[United States Census Bureau]]. Accessed August 16, 2022.</ref>

;K-12
{{div col|colwidth=30em}}
* [[East Windsor Regional School District]]
* [[Ewing Public Schools]]
* [[Hamilton Township School District]]
* [[Hopewell Valley Regional School District]]
* [[Lawrence Township Public Schools]]
* [[Mercer County Special Services School District]]
* [[Princeton Public Schools]]
* [[Robbinsville Public School District]]
* [[Trenton Public Schools]]
* [[West Windsor-Plainsboro Regional School District]]
{{div col end}}

;9-12
* [[Mercer County Technical Schools]]

;Special
There is a state-operated school, [[Marie H. Katzenbach School for the Deaf]].

===Higher education===
Mercer County is home to [[Princeton University]], [[Princeton Theological Seminary]], the [[Institute for Advanced Study]], [[Rider University]], [[Westminster Choir College]], [[The College of New Jersey]], and [[Thomas Edison State University]]. [[Mercer County Community College]] is a county-run community college located in West Windsor.<ref>[http://www.state.nj.us/counties/mercer/about/ About Mercer County] {{webarchive|url=https://web.archive.org/web/20090328011955/http://www.state.nj.us/counties/mercer/about/ |date=March 28, 2009 }}, Mercer County. Accessed January 11, 2015.</ref>

==Points of interest==
* [[Drumthwacket]], The official residence of the Governor of New Jersey located in [[Princeton, New Jersey|Princeton]]
* [[New Jersey State House]], The capitol complex of New Jersey and the meeting point of the state legislature, located at the state capital in [[Trenton, New Jersey|Trenton]]
* [[Mercer County Park]], in [[West Windsor, New Jersey|West Windsor]]
* Hamilton Veterans Park
* Mercer County Park September 11 Memorial<ref>{{Cite web |title=MCCC - MCCC prepares to honor the victims of 9/11 by maintaining a focus on unity remembrance and service |url=https://mccc.edu/pr/General/2020/911_video.html |access-date=2024-05-09 |website=mccc.edu}}</ref>
* [[Swaminarayan Akshardham (North America)|Swaminarayan Akshardham]] in [[Robbinsville, New Jersey|Robbinsville]], the [[list of largest Hindu temples|largest Hindu temple outside Asia]]
* [[Assunpink Creek]] (part)
* [[Mercer Lake]] at Mercer County Park
* Griggstown Native Grassland Preserve (part)
* [[Princeton Battlefield]]
* Mercer Oaks Golf Course
* [[Washington Crossing State Park]], in Hopewell Township 
* Colonial Memorial Park in Trenton
* [[Lower Trenton Bridge]]
* [[Trenton War Memorial]]
* [[Trenton Thunder Ballpark]]
* Grounds for Sculpture, in Hamilton Township 

===Wineries===
* Hopewell Valley Vineyards
* Working Dog Winery, in East Windsor Township

==See also==
{{portal|New Jersey}}
* [[National Register of Historic Places listings in Mercer County, New Jersey]]

==Notes==
{{Reflist|group=note}}

==References==
{{Reflist}}

==External links==
{{Commons category}}
{{Wikivoyage|Mercer County (New Jersey)}}
* [http://www.mercercounty.org/ Official County Website]
* [https://www.mcl.org/ Mercer County Library System]

{{Geographic location
|Centre    = Mercer County, New Jersey
|North     = [[Somerset County, New Jersey|Somerset County]]
|Northeast =
|East      = [[Middlesex County, New Jersey|Middlesex County]]
|Southeast = [[Monmouth County, New Jersey|Monmouth County]]
|South     = [[Burlington County, New Jersey|Burlington County]]
|Southwest =
|West      = [[Bucks County, Pennsylvania|Bucks County]]
|Northwest = [[Hunterdon County, New Jersey|Hunterdon County]]
}}
{{Delaware Valley}}
{{Raritan Valley navigation}}
{{Mercer County, New Jersey}}
{{New Jersey}}
{{New York metropolitan area}}
{{authority control}}

[[Category:Mercer County, New Jersey| ]]
[[Category:1838 establishments in New Jersey]]
[[Category:Central Jersey]]
[[Category:Counties in the New York metropolitan area]]
[[Category:Populated places established in 1838]]