Editing Interstate Highway System (section)

===Speed limits===
{{Further|Speed limits in the United States|National Maximum Speed Law}}
[[File:2019-07-15 11 10 50 View south along Interstate 95 from the overpass for Maryland State Route 175 (Waterloo Road-Rouse Parkway) in Columbia, Howard County, Maryland.jpg|alt=|thumb|[[Interstate 95 in Maryland|I-95]] in [[Columbia, Maryland]], built to modern standards.]]
[[File:Interstate_5_in_the_Central_Valley.jpg|thumb|right|A rural stretch of [[Interstate 5 in California|I-5]] in California; two lanes in each direction are separated by a large grassy [[central reservation|median]] and cross-traffic is limited to [[grade separation]]s such as this overpass.]]
Being [[freeway]]s, Interstate Highways usually have the highest [[speed limit]]s in a given area. Speed limits are determined by individual states. From 1975 to 1986, the maximum speed limit on any highway in the United States was {{Convert|55|mi/h|km/h|round=5}}, in accordance with federal law.<ref name="nytimes3a">{{cite news |title = Nixon Approves Limit of 55 M.P.H. |url = http://select.nytimes.com/gst/abstract.html?res=F40610FD3F58137B93C1A9178AD85F408785F9&scp=1&sq=nixon%20approves%20limit%20of%2055&st=cse |access-date = July 27, 2008 |work = The New York Times |pages = 1, 24 |date = January 3, 1974 |url-access = subscription |archive-url = https://web.archive.org/web/20110605095932/http://select.nytimes.com/gst/abstract.html?res=F40610FD3F58137B93C1A9178AD85F408785F9&scp=1&sq=nixon%20approves%20limit%20of%2055&st=cse |archive-date= June 5, 2011 |url-status= dead}}</ref>

Typically, lower limits are established in [[Northeastern United States|Northeastern]] and coastal states, while higher speed limits are established in inland states west of the [[Mississippi River]].<ref name="mit">{{cite web |url = https://www.mit.edu/~jfc/laws.html |title = State traffic and speed laws |date = October 11, 2007 |access-date = January 10, 2008 |publisher = Massachusetts Institute of Technology |last = Carr |first = John |archive-url = https://web.archive.org/web/20130807221607/http://www.mit.edu/~jfc/laws.html |archive-date = August 7, 2013 |url-status = live }}</ref> For example, the maximum speed limit is {{convert|75|mph|km/h|round=5|abbr=on}} in northern Maine, varies between {{convert|50|and|70|mph|km/h|round=5|abbr=on}}<ref>{{cite news |first = Paul |last = Koenig |date = May 27, 2014 |title = Speed Limit on Much of I-295 Rises to 70&nbsp;MPH |url = http://www.pressherald.com/2014/05/27/speed_limt_on_much_of_maine_turnpike__i-295_ro_rise_to_70_mph/ |work = [[Portland Press Herald]] |access-date = July 22, 2014 |archive-url = https://web.archive.org/web/20140727171449/http://www.pressherald.com/2014/05/27/speed_limt_on_much_of_maine_turnpike__i-295_ro_rise_to_70_mph/ |archive-date = July 27, 2014 |url-status = live }}</ref> from southern Maine to New Jersey, and is {{convert|50|mph|km/h|round=5|abbr=on}} in New York City and the District of Columbia.<ref name="mit" /> Currently, rural speed limits elsewhere generally range from {{convert|65|to|80|mph|km/h|round=5}}. Several portions of various highways such as [[Interstate 10 in Texas|I-10]] and [[Interstate 20 in Texas|I-20]] in rural western Texas, [[Interstate 80 in Nevada|I-80]] in Nevada between Fernley and Winnemucca (except around Lovelock) and portions of [[Interstate 15 in Utah|I-15]], [[Interstate 70 in Utah|I-70]], [[Interstate 80 in Utah|I-80]], and [[Interstate 84 in Utah|I-84]] in Utah have a speed limit of {{convert|80|mph|km/h|round=5|abbr=on}}. Other Interstates in Idaho, Montana, Oklahoma, South Dakota and Wyoming also have the same high speed limits.

In some areas, speed limits on Interstates can be significantly lower in areas where they traverse significantly hazardous areas. The maximum speed limit on [[Interstate 90 in Ohio|I-90]] is {{convert|50|mph|km/h|round=5|abbr=on}} in downtown [[Cleveland]] because of two sharp curves with a suggested limit of {{convert|35|mph|km/h|round=5|abbr=on}} in a heavily congested area; [[Interstate 70 in West Virginia|I-70]] through [[Wheeling, West Virginia]], has a maximum speed limit of {{convert|45|mph|km/h|round=5|abbr=on}} through the [[Wheeling Tunnel]] and most of downtown Wheeling; and [[Interstate 68|I-68]] has a maximum speed limit of {{convert|40|mph|km/h|round=5|abbr=on}} through [[Cumberland, Maryland]], because of multiple hazards including sharp curves and narrow lanes through the city. In some locations, low speed limits are the result of lawsuits and resident demands; after holding up the completion of [[Interstate 35E (Minnesota)|I-35E]] in [[St. Paul, Minnesota]], for nearly 30&nbsp;years in the courts, residents along the stretch of the freeway from the southern city limit to downtown successfully lobbied for a {{convert|45|mph|km/h|round=5|abbr=on}} speed limit in addition to a prohibition on any vehicle weighing more than {{convert|9,000|lbs|kg}} [[gross vehicle weight]]. [[Interstate 93|I-93]] in [[Franconia Notch State Park]] in northern New Hampshire has a speed limit of {{convert|45|mph|km/h|round=5|abbr=on}} because it is a parkway that consists of only one lane per side of the highway. On the other hand, Interstates 15, 80, 84, and 215 in Utah have speed limits as high as {{convert|70|mph|km/h|round=5|abbr=on}} within the [[Wasatch Front]], [[Cedar City, Utah|Cedar City]], and [[St. George, Utah|St. George]] areas, and [[Interstate 25 in New Mexico|I-25]] in New Mexico within the [[Santa Fe, New Mexico|Santa Fe]] and [[Las Vegas, New Mexico|Las Vegas]] areas along with [[Interstate 20 in Texas|I-20]] in Texas along Odessa and [[Midland, Texas|Midland]] and [[Interstate 29 in North Dakota|I-29]] in North Dakota along the [[Grand Forks, North Dakota|Grand Forks]] area have higher speed limits of {{convert|75|mph|km/h|round=5|abbr=on}}.