United States

== Geography ==
{{Main|Geography of the United States|Borders of the United States}}

[[File:Uspaintedrelief.png|thumb|A [[topographic map]] of the United States]]

The United States is the world's [[List of countries and dependencies by area|third-largest country]] by total area behind Russia and Canada.{{efn|name=largestcountry}}<ref name="WF">{{cite web|url=https://www.cia.gov/the-world-factbook/countries/united-states/|title=United States|website=The World Factbook|publisher=Central Intelligence Agency|date=January 3, 2018|access-date=January 8, 2018}}</ref><ref name="CIA Factbook Area">{{cite web|title=Area|url=https://www.cia.gov/library/publications/the-world-factbook/fields/2147.html|website=The World Factbook|publisher=Central Intelligence Agency|access-date=January 15, 2015|archive-date=January 31, 2014|archive-url=https://web.archive.org/web/20140131115000/https://www.cia.gov/library/publications/the-world-factbook/fields/2147.html|url-status=dead }}</ref> The [[Contiguous United States|48 contiguous states and the District of Columbia]] occupy a combined area of {{convert|3,119,885|sqmi|km2|abbr=}}.<ref>{{cite web|url=https://www.cia.gov/library/publications/the-world-factbook/fields/279.html#as|work=The World Factbook|publisher=cia.gov|title=Field Listing: Area|access-date=April 21, 2020|archive-date=July 7, 2020|archive-url=https://web.archive.org/web/20200707180005/https://www.cia.gov/library/publications/the-world-factbook/fields/279.html#as|url-status=dead}}</ref><ref name="urlState Area Measurements and Internal Point Coordinates—Geography—U.S. Census Bureau">{{cite web|url=https://www.census.gov/geographies/reference-files/2010/geo/state-area.html|title=State Area Measurements and Internal Point Coordinates—Geography—U.S. Census Bureau|website=State Area Measurements and Internal Point Coordinates|publisher=U.S. Department of Commerce|access-date=September 11, 2017}}</ref> The [[Atlantic coastal plain|coastal plain]] of the [[Atlantic Ocean|Atlantic]] seaboard gives way to inland forests and rolling hills in the [[Piedmont (United States)|Piedmont]] plateau region.<ref>{{cite web|title=Geographic Regions of Georgia|url=https://georgiainfo.galileo.usg.edu/topics/geography/article/geographic-regions-of-georgia|website=Georgia Info|publisher=Digital Library of Georgia|access-date=December 24, 2014}}</ref>

The [[Appalachian Mountains]] and the [[Adirondack Mountains|Adirondack]] massif separate the [[East Coast of the United States|East Coast]] from the [[Great Lakes]] and the grasslands of the [[Midwestern United States|Midwest]].<ref name="NAU">{{cite web|last=Lew|first=Alan|title=PHYSICAL GEOGRAPHY OF THE US|url=https://www.geog.nau.edu/courses/alew/gsp220/text/chapters/ch2.html|archive-url=https://web.archive.org/web/20160409112252/https://www.geog.nau.edu/courses/alew/gsp220/text/chapters/ch2.html|archive-date=April 9, 2016|website=GSP 220—Geography of the United States|publisher=North Arizona University|access-date=December 24, 2014}}</ref> The [[Mississippi River System]], the world's [[List of rivers by length|fourth-longest river system]], runs predominantly north–south through the heart of the country. The flat and fertile [[prairie]] of the [[Great Plains]] stretches to the west, interrupted by [[U.S. Interior Highlands|a highland region]] in the southeast.<ref name="NAU" />

[[File:Grand Canyon National Park — Buddha Temple.jpg|thumb|The [[Grand Canyon]] in [[Arizona]]]]
The [[Rocky Mountains]], west of the Great Plains, extend north to south across the country, peaking at over {{convert|14000|ft}} in [[Colorado]].<ref>{{cite web|last=Harms|first=Nicole|title=Facts About the Rocky Mountain Range|url=https://traveltips.usatoday.com/rocky-mountain-range-11967.html|work=USA Today|access-date=December 24, 2014}}</ref> Farther west are the rocky [[Great Basin]] and [[Chihuahuan Desert|Chihuahua]], [[Sonoran Desert|Sonoran]], and [[Mojave Desert|Mojave]] deserts.<ref>{{cite journal|last=Tinkham|first=Ernest R.|title=Biological, Taxonomic and Faunistic Studies on the Shield-Back Katydids of the North American Deserts|jstor=2421073|doi=10.2307/2421073|journal=[[The American Midland Naturalist]]|volume=31|number=2|date=March 1944|pages=257–328|publisher=The [[University of Notre Dame]]}}</ref> In the northwest corner of [[Arizona]], carved by the [[Colorado River]] over millions of years, is the [[Grand Canyon]], a steep-sided canyon and popular tourist destination known for its overwhelming visual size and intricate, colorful landscape.

The [[Sierra Nevada (U.S.)|Sierra Nevada]] and [[Cascade Range|Cascade]] mountain ranges run close to the [[West Coast of the United States|Pacific coast]]. The [[Extreme points of the United States|lowest and highest points]] in the contiguous United States are in the state of California,<ref>{{cite web|title=Mount Whitney, California|url=https://www.peakbagger.com/peak.aspx?pid=2829|publisher=Peakbagger|access-date=December 24, 2014}}</ref> about {{convert|84|mi|km}} apart.<ref>{{cite web|title=Find Distance and Azimuths Between 2 Sets of Coordinates (Badwater 36-15-01-N, 116-49-33-W and Mount Whitney 36-34-43-N, 118-17-31-W)|url=https://transition.fcc.gov/fcc-bin/distance?dlat=36&mlat=15&slat=01&ns=1&dlon=116&mlon=49&slon=33&ew=1&dlat2=36&mlat2=34&slat2=43&sn=1&dlon2=118&mlon2=17&slon2=31&we=1&iselec=1|publisher=Federal Communications Commission|access-date=December 24, 2014}}</ref> At an elevation of {{convert|20310|ft|1}}, Alaska's [[Denali]] is the highest peak in the country and continent.<ref>{{cite web|last=Poppick|first=Laura|title=US Tallest Mountain's Surprising Location Explained|date=August 28, 2013|url=https://www.livescience.com/39245-us-tallest-mountain-location-explained.html|publisher=LiveScience|access-date=May 2, 2015}}</ref> Active [[volcano]]es are common throughout Alaska's [[Alexander Archipelago|Alexander]] and [[Aleutian Islands]], and Hawaii consists of volcanic islands. The [[supervolcano]] underlying [[Yellowstone National Park]] in the [[Rockies]] is the continent's largest volcanic feature.<ref>{{cite web|last=O'Hanlon|first=Larry|title=America's Explosive Park|url=https://dsc.discovery.com/convergence/supervolcano/under/under.html|date=March 14, 2005|archive-url=https://web.archive.org/web/20050314034001/https://dsc.discovery.com/convergence/supervolcano/under/under.html|archive-date=March 14, 2005|publisher=Discovery Channel|access-date=April 5, 2016}}</ref> In 2021, the United States had 8% of global permanent meadows and pastures and 10% of cropland.<ref name=":14">{{Cite book |title=World Food and Agriculture – Statistical Yearbook 2023 |publisher=Food and Agriculture Organization of the United Nations |url=https://www.fao.org/documents/card/en?details=cc8166en |access-date=2023-12-13 | date=2023 |language=en |doi=10.4060/cc8166en| isbn=978-92-5-138262-2 }}</ref>

=== Climate ===
{{Main|Climate of the United States|Climate change in the United States}}
[[File:Köppen Climate Types US 50.png|thumb|The [[Köppen climate classification|Köppen climate types]] of the United States]]

With its large size and geographic variety, the United States includes most climate types. East of the [[100th meridian west|100th meridian]], the climate ranges from [[humid continental climate|humid continental]] in the north to [[humid subtropical climate|humid subtropical]] in the south.<ref>{{cite web|last=Boyden|first=Jennifer|title=Climate Regions of the United States|url=https://traveltips.usatoday.com/climate-regions-united-states-21570.html|work=USA Today|access-date=December 24, 2014}}</ref> The western Great Plains are [[Semi-arid climate|semi-arid]]. Many mountainous areas of the American West have an [[alpine climate]]. The climate is [[Desert climate|arid]] in the Southwest, [[Mediterranean climate|Mediterranean]] in [[coastal California]], and [[oceanic climate|oceanic]] in coastal [[Oregon]], [[Washington (state)|Washington]], and southern [[Alaska]]. Most of Alaska is [[Subarctic climate|subarctic]] or [[Polar climate|polar]]. [[Hawaii]], the [[South Florida|southern tip of Florida]] and U.S. territories in the [[Caribbean]] and [[Pacific Ocean|Pacific]] are [[Tropical climate|tropical]].<ref>{{cite web|title=World Map of Köppen–Geiger Climate Classification|url=https://koeppen-geiger.vu-wien.ac.at/pdf/kottek_et_al_2006_A4.pdf|access-date=August 19, 2015|archive-date=January 26, 2022|archive-url=https://web.archive.org/web/20220126115149/http://koeppen-geiger.vu-wien.ac.at/pdf/kottek_et_al_2006_A4.pdf|url-status=dead}}</ref>

States bordering the [[Gulf of Mexico]] are prone to [[Tropical cyclone|hurricanes]], and most of the world's [[Tornadoes in the United States|tornadoes]] occur in the country, mainly in [[Tornado Alley]].<ref>{{cite news|author=Perkins, Sid|url=https://www.sciencenews.org/articles/20020511/bob9.asp|archive-url=https://web.archive.org/web/20070701131631/https://www.sciencenews.org/articles/20020511/bob9.asp|archive-date=July 1, 2007|title=Tornado Alley, USA|access-date=September 20, 2006|date=May 11, 2002|work=Science News}}</ref> Overall, the United States receives more high-impact extreme weather incidents than any other country.<ref>{{cite web|title=USA has the world's most extreme weather|url=https://www.usatoday.com/story/weather/2013/05/16/extreme-weather-north-america/2162501/|last=Rice|first=Doyle|website=USA Today|language=en|access-date=May 17, 2020}}</ref> Extreme weather became more frequent in the U.S. in the 21st century, with three times the number of reported [[heat waves]] as in the 1960s. In the [[Southwestern United States|American Southwest]], droughts became more persistent and more severe.<ref>{{Cite web|last=US EPA|first=OAR|date=June 27, 2016|title=Climate Change Indicators: Weather and Climate|url=https://www.epa.gov/climate-indicators/weather-climate|access-date=June 19, 2022|website=Epa.gov|language=en}}</ref>

=== Biodiversity and conservation ===
{{Main|Fauna of the United States|Flora of the United States}}
{{Anchor|Wildlife and conservation}}
[[File:Bald eagle about to fly in Alaska (2016).jpg|alt=A bald eagle|thumb|The [[bald eagle]], the [[national bird of the United States]] since 1782<ref name="McDougall2004">{{cite book|first=Len|last=McDougall|title=The Encyclopedia of Tracks and Scats: A Comprehensive Guide to the Trackable Animals of the United States and Canada|url=https://books.google.com/books?id=9XOc2_u7z6cC&pg=PA325|year=2004|publisher=Lyons Press|isbn=978-1-59228-070-4|page=325}}</ref>]]

The U.S. is one of 17 [[megadiverse countries]] containing large numbers of [[List of endangered animals of North America|endemic species]]: about 17,000 species of [[vascular plant]]s occur in the contiguous United States and Alaska, and over 1,800 species of [[flowering plant]]s are found in Hawaii, few of which occur on the mainland.<ref>{{cite web|author=Morin, Nancy|url=https://www.fungaljungal.org/papers/National_Biological_Service.pdf|archive-url=https://web.archive.org/web/20130724222726/https://www.fungaljungal.org/papers/National_Biological_Service.pdf|title=Vascular Plants of the United States|website=Plants|publisher=National Biological Service|access-date=October 27, 2008|archive-date=July 24, 2013}}</ref> The United States is home to 428 [[mammal]] species, 784 birds, 311 reptiles, 295 [[amphibian]]s,<ref name="Current Results # of native species in the US">{{cite web|last1=Osborn|first1=Liz|title=Number of Native Species in United States|url=https://www.currentresults.com/Environment-Facts/Plants-Animals/number-of-native-species-in-united-states.php|publisher=Current Results Nexus|access-date=January 15, 2015}}</ref> and 91,000 insect species.<ref>{{cite web|url=https://www.si.edu/Encyclopedia_SI/nmnh/buginfo/bugnos.htm|title=Numbers of Insects (Species and Individuals)|publisher=Smithsonian Institution|access-date=January 20, 2009}}</ref>

There are 63 [[List of national parks of the United States|national parks]], and [[Federal lands|hundreds of other federally managed]] parks, forests, and [[National Wilderness Preservation System|wilderness areas]], managed by the [[National Park Service]] and other agencies.<ref>{{cite web|title= National Park FAQ|url=https://www.nps.gov/aboutus/national-park-system.htm/|website=nps|publisher=National Park Service|access-date=May 8, 2015}}</ref> About 28% of the country's land is publicly owned and federally managed,<ref name="NYTimes Federal Land">{{cite news|last1=Lipton|first1=Eric|last2=Krauss|first2=Clifford|title=Giving Reins to the States Over Drilling|url=https://www.nytimes.com/2012/08/24/us/romney-would-give-reins-to-states-on-drilling-on-federal-lands.html?pagewanted=2&_r=0|access-date=January 18, 2015|newspaper=The New York Times|date=August 23, 2012}}</ref> primarily in the [[Western United States|western states]].<ref name="AKLeg CRS Federal Land">{{Cite report|url=https://www.akleg.gov/basis/get_documents.asp?session=31&docid=47224|title=Federal Land Ownership: Overview and Data|publisher=Congressional Research Service|date=March 3, 2017|access-date=June 18, 2020|last1=Vincent|first1=Carol H.|last2=Hanson|first2=Laura A.|last3=Argueta|first3=Carla N.|page=2}}</ref> Most of this land is [[Protected areas of the United States|protected]], though some is leased for commercial use, and less than one percent is used for military purposes.<ref name="Federal Land Ownership">{{cite web|last1=Gorte|first1=Ross W.|last2=Vincent|first2=Carol Hardy.|last3=Hanson|first3=Laura A.|last4=Marc R.|first4=Rosenblum|title=Federal Land Ownership: Overview and Data|url=https://fas.org/sgp/crs/misc/R42346.pdf|website=fas.org|publisher=Congressional Research Service|access-date=January 18, 2015}}</ref><ref name="Fed Land Uses">{{cite web|title=Chapter 6: Federal Programs to Promote Resource Use, Extraction, and Development|url=https://www.doi.gov/pmb/oepc/wetlands2/v2ch6.cfm|website=doi.gov|archive-url=https://web.archive.org/web/20150318005744/https://www.doi.gov/pmb/oepc/wetlands2/v2ch6.cfm|publisher=U.S. Department of the Interior|access-date=January 19, 2015|archive-date=March 18, 2015}}</ref>

[[Environmental issues in the United States]] include debates on [[non-renewable resource]]s and [[Nuclear power debate|nuclear energy]], [[Pollution prevention in the US|air and water pollution]], [[biodiversity]], logging and [[Deforestation in the United States|deforestation]],<ref>{{cite web|author=The National Atlas of the United States of America|url=https://www.nationalatlas.gov/articles/biology/a_forest.html|title=Forest Resources of the United States|publisher=Nationalatlas.gov|date=January 14, 2013|access-date=January 13, 2014|archive-url=https://web.archive.org/web/20090507195541/https://www.nationalatlas.gov/articles/biology/a_forest.html|archive-date=May 7, 2009 }}</ref><ref>{{cite web|url=https://www.fs.fed.us/pnw/pubs/gtr587.pdf|title=Land Use Changes Involving Forestry in the United States: 1952 to 1997, With Projections to 2050|year=2003|access-date=January 13, 2014}}</ref> and [[Climate change in the United States|climate change]].<ref>[[#Daynes|Daynes & Sussman, 2010]], pp. 3, 72, 74–76, 78</ref><ref>Hays, Samuel P. (2000). ''A History of Environmental Politics since 1945''.</ref> The [[United States Environmental Protection Agency|U.S. Environmental Protection Agency]] (EPA) is the federal agency charged with [[Environmental policy of the United States|addressing most environmental-related issues]].<ref name="Collin2006">{{cite book|last=Collin|first=Robert W.|title=The Environmental Protection Agency: Cleaning Up America's Act|url=https://books.google.com/books?id=OVPoqXeTYTwC&pg=PA1|year=2006|publisher=Greenwood Publishing Group|isbn=978-0-313-33341-5|page=1|access-date=October 25, 2015}}</ref> The [[National Wilderness Preservation System|idea of wilderness]] has shaped the management of public lands since 1964, with the [[Wilderness Act]].<ref>Turner, James Morton (2012). ''The Promise of Wilderness'', pp. 29&ndash;32</ref> The [[Endangered Species Act of 1973]] provides a way to protect threatened and endangered species and their habitats. The [[United States Fish and Wildlife Service]] implements and enforces the Act.<ref name="Office">{{cite book|title=Endangered species Fish and Wildlife Service|url=https://books.google.com/books?id=a8BEuUPJb58C&pg=PA1|publisher=General Accounting Office, Diane Publishing|isbn=978-1-4289-3997-4|pages=1–3, 42|access-date=October 25, 2015|year=2003 }}</ref> {{As of|2022}}, the U.S. ranked 43rd among 180 countries in the [[Environmental Performance Index]].<ref>{{Cite web|url=https://epi.yale.edu/epi-results/2022/component/epi|title=Environmental Performance Index &#124; Environmental Performance Index|website=epi.yale.edu}}</ref> The country joined the [[Paris Agreement]] on climate change in 2016 and has many other environmental commitments.<ref>{{cite web|title=United States of America|url=https://climateaction.unfccc.int/views/country.html?country=US|website=Global Climate Action – NAZCA|publisher=United Nations|access-date=November 18, 2020}}</ref>