United States

mostly temperate, but tropical in Hawaii and Florida, arctic in Alaska, semiarid in the great plains west of the Mississippi River, and arid in the Great Basin of the southwest; low winter temperatures in the northwest are ameliorated occasionally in January and February by warm chinook winds from the eastern slopes of the Rocky Mountains

note: many consider Mount McKinley, the highest peak in the United States, to be the world’s coldest mountain because of its combination of high elevation and its subarctic location at 63 degrees north latitude; permanent snow and ice cover over 75 percent of the mountain, and enormous glaciers, up to 45 miles long and 3,700 feet thick, spider out from its base in every direction; it is home to some of the world’s coldest and most violent weather, where winds of over 150 miles per hour and temperatures of -93˚F have been recorded.

vast central plain, mountains in west, hills and low mountains in east; rugged mountains and broad river valleys in Alaska; rugged, volcanic topography in Hawaii

North America, bordering both the North Atlantic Ocean and the North Pacific Ocean, between Canada and Mexico

19,924 km

234,782 sq km (2017)

Northern Great Plains Aquifer, Cambrian-Ordovician Aquifer System, Californian Central Valley Aquifer System, Ogallala Aquifer (High Plains), Atlantic and Gulf Coastal Plains Aquifer

North America

tsunamis; volcanoes; earthquake activity around Pacific Basin; hurricanes along the Atlantic and Gulf of America coasts; tornadoes in the Midwest and Southeast; mud slides in California; forest fires in the west; flooding; permafrost in northern Alaska is a major impediment to development volcanism: volcanic activity in the Hawaiian Islands, Western Alaska, the Pacific Northwest, and in the Northern Mariana Islands; Mauna Loa (4,170 m) in Hawaii and Mount Rainier (4,392 m) in Washington have been deemed Decade Volcanoes by the International Association of Volcanology and Chemistry of the Earth's Interior, worthy of study due to their explosive history and close proximity to human populations; Pavlof (2,519 m) is the most active volcano in Alaska's Aleutian Arc and poses a significant threat to intercontinental air travel; St. Helens (2,549 m), famous for the devastating 1980 eruption, remains active today; other historically active volcanoes are mostly concentrated in the Aleutian arc and Hawaii, including (in Alaska) Aniakchak, Augustine, Chiginagak, Fourpeaked, Iliamna, Katmai, Kupreanof, Martin, Novarupta, Redoubt, Spurr, Wrangell, Trident, Ugashik-Peulik, Ukinrek Maars, Veniaminof, (in Hawaii) Haleakala, Kilauea, Loihi, (in the Northern Mariana Islands) Anatahan, (in the Pacific Northwest) Mount Baker, and Mount Hood; see note 2 under "Geography - note"

note 1: world's third-largest country by size (after Russia and Canada) and by population (after China and India); Mt. McKinley is the highest point (6,190 m; 20,308 ft) in North America, and Death Valley is the lowest point (-86 m; -282 ft) note 2: the western US coast and the southern coast of Alaska lie along the Ring of Fire, which is a belt bordering the Pacific Ocean that contains about 75% of the world's volcanoes and up to 90% of the world's earthquakes note 3: the Aleutian Islands are a chain of volcanic islands that divide the Bering Sea (north) from the main Pacific Ocean (south); they extend about 1,800 km (1,118 mi) westward from the Alaskan Peninsula; the archipelago consists of 14 larger islands, 55 smaller islands, and hundreds of islets; there are 41 active volcanoes on the islands, which together form a large northern section of the Ring of Fire note 4: Mammoth Cave, in west-central Kentucky, is the world's longest known cave system with more than 650 km (405 miles) of surveyed passageways, which is nearly twice as long as the second-longest cave system, the Sac Actun underwater cave in Mexico (see "Geography - note" under Mexico) note 5: Kazumura Cave on the island of Hawaii is the world's longest and deepest lava-tube cave; it has been surveyed at 66 km (41 mi) long and 1,102 m (3,614 ft) deep note 6: Bracken Cave outside San Antonio, Texas is the world's largest bat cave and the summer home to the largest colony of bats in the world; an estimated 20 million Mexican free-tailed bats roost in the cave from March to October, making it the world's largest known concentration of mammals

coal, copper, lead, molybdenum, phosphates, rare earth elements, uranium, bauxite, gold, iron, mercury, nickel, potash, silver, tungsten, zinc, petroleum, natural gas, timber, arable land

note: the US has the world's largest coal reserves with 491 billion short tons accounting for 27% of the world's total

about half the size of Russia; about three-tenths the size of Africa; about half the size of South America (or slightly larger than Brazil); slightly larger than China; more than twice the size of the European Union

38 00 N, 97 00 W

large urban clusters are spread throughout the eastern half of the US (particularly the Great Lakes area, northeast, east, and southeast) and the western-tier states; mountainous areas such as the Rocky Mountains and Appalachians, deserts in the southwest, the dense boreal forests in the extreme north, and the central prairie states are less densely populated; Alaska's population is concentrated along its southern coast, particularly around Anchorage, and Hawaii's is centered on the island of Oahu

Missouri - 3,768 km; Mississippi - 3,544 km; Yukon river mouth (shared with Canada [s]) - 3,190 km; Saint Lawrence (shared with Canada) - 3,058 km; Rio Grande river source (mouth shared with Mexico) - 3,057 km; Colorado river source (shared with Mexico [m]) - 2,333 km; Arkansas - 2,348 km; Columbia river mouth (shared with Canada [s]) - 2,250 km; Red - 2,188 km; Ohio - 2,102 km); Snake - 1,670 km note: [s] after country name indicates river source; [m] after country name indicates river mouth