Editing Fairfax County, Virginia (section)

== Geography and climate==
{{Location map+ | Fairfax Area
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|width=400
| places =
 {{Location map~ | Fairfax Area
 | label =[[Montgomery County, Maryland|Montgomery]]
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 | lat_deg =38.98
 | lon_deg =-77.119
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 {{Location map~ | Fairfax Area
 | label =[[Alexandria, Virginia|Alexandria]]
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 | lon_deg =-77.047222
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 {{Location map~ | Fairfax Area
 | label =[[Arlington County, Virginia|Arlington]]
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 | lat_deg =38.87
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 {{Location map~ | Fairfax Area
 | label =[[Fairfax, Virginia|Fairfax]]
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 {{Location map~ | Fairfax Area
 | label =Fairfax{{nbsp}}County
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 | lat_deg =38.83
 | lon_deg =-77.28
 }}
 {{Location map~ | Fairfax Area
 | label =[[Falls Church, Virginia|Falls{{nbsp}}Church]]
 | label_size=100
 | marksize=5
 | position =left
 | lat_deg =38.882222
 | lon_deg =-77.171111
 }}
 {{Location map~ | Fairfax Area
 | label =[[Loudoun County, Virginia|Loudoun]]
 | label_size=100
 | marksize=0
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 | lat_deg =38.946264
 | lon_deg =-77.456541
 }}
 {{Location map~ | Fairfax Area
 | label =[[Manassas, Virginia|Manassas]]
 | label_size=100
 | marksize=5
 | position =right
 | lat_deg =38.754427
 | lon_deg =-77.463920
 }}
 {{Location map~ | Fairfax Area
 | label =[[Manassas Park, Virginia|Manassas{{nbsp}}Park]]
 | label_size=100
 | marksize=5
 | position =right
 | lat_deg =38.781529
 | lon_deg =-77.440528
 }}
 {{Location map~ | Fairfax Area
 | label =[[Prince William County, Virginia|Prince{{nbsp}}William]]
 | label_size=100
 | marksize=0
 | position =right
 | lat_deg =38.722645
 | lon_deg =-77.356234
 }}
 {{Location map~ | Fairfax Area
 | label =[[Washington, D.C.|Washington]]
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 | position =left
 | lat_deg =38.910748
 | lon_deg =-77.07
 }}
}}

According to the [[United States Census Bureau|U.S. Census Bureau]], the county has an area of {{convert|406|sqmi}}, of which {{convert|391|sqmi}} is land and {{convert|15|sqmi}} (3.8%) is water.<ref name="GR1">{{cite web|url=https://www.census.gov/geographies/reference-files/time-series/geo/gazetteer-files.html|publisher=[[United States Census Bureau]]|access-date=April 23, 2011|date=February 12, 2011|title=US Gazetteer files: 2010, 2000, and 1990}}</ref> There are about 44,400,000 trees that create a canopy covering 55.4% of the total land area.<ref>{{cite web |title=Natural Resources Metrics |url=https://www.fairfaxcounty.gov/environment-energy-coordination/climate-action/natural-resources |publisher=County of Fairfax Virginia |access-date=1 October 2024}}</ref>

Fairfax County is bounded on the north and southeast by the [[Potomac River]]. Across the river to the northeast is [[Washington, D.C.]], across the river to the north is [[Montgomery County, Maryland]], and across the river to the southeast are [[Prince George's County, Maryland]] and [[Charles County, Maryland]]. The county is partially bounded on the north and east by [[Arlington County, Virginia|Arlington County]] and the independent cities of [[Alexandria, Virginia|Alexandria]] and [[Falls Church, Virginia|Falls Church]]. It is bounded on the west by [[Loudoun County, Virginia|Loudoun County]], and on the south by [[Prince William County, Virginia|Prince William County]].

Most of the county lies in the [[Piedmont (United States)|Piedmont]] region, with rolling hills and deep stream valleys, such as [[Difficult Run]] and its tributaries. West of [[Virginia State Route 28|Route 28]], the hills give way to a flat, gentle valley that stretches west to the [[Bull Run Mountains]] in Loudoun County. Elevations in the county range from near sea level along the tidal sections of the Potomac River in the southeast portion of the county to more than {{convert|500|ft|m}} in the [[Tysons, Virginia|Tysons]] area.

In 2023, the plant [[hardiness zone]] shifted from 7a to 7b. The Fairfax County News Letter predicts that Fairfax will shift to zone 8 in the next few decades as temperatures rise.<ref>{{cite web |title=Tree Planting Season Shifts Due to Changing Climate |url=https://www.fairfaxcounty.gov/news/tree-planting-season-shifts-due-changing-climate |website=County of Fairfax Virginia |access-date=3 October 2024}}</ref>

=== Adjacent jurisdictions ===
{{columns-list|colwidth=20em| 
* [[Alexandria, Virginia|Alexandria]] – east
* [[Arlington County, Virginia|Arlington County]] – east
* [[Charles County, Maryland]] – southeast
* [[Fairfax, Virginia|Fairfax]] – surrounded by Fairfax County
* [[Falls Church, Virginia|Falls Church]] – east
* [[Loudoun County, Virginia|Loudoun County]] – northwest
* [[Montgomery County, Maryland]] – north
* [[Prince George's County, Maryland]] – east
* [[Prince William County, Virginia|Prince William County]] – southwest
}}