United States

=== 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>