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Contiguous United States

48 states of the US apart from Alaska and Hawaii

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Through North America, Russia and Canada

The greatest distance on a great-circle route entirely within the contiguous U.S. is 2,802 miles (4,509 km), coast-to-coast between Florida and Washington state; the greatest north–south line is 1,650 miles (2,660 km). The contiguous United States occupies an area of 3,119,884.69 square miles (8,080,464.3 km2). Of this area, 2,959,064.44 square miles (7,663,941.7 km2) is actual land, composing 83.65 percent of the country's total land area, and is comparable in size to the area of Australia. Officially, 160,820.25 square miles (416,522.5 km2) of the contiguous United States is water area, composing 62.66 percent of the nation's total water area.

If just the contiguous United States were a country, it would be fifth on the list of countries and dependencies by area, behind Russia (Europe and Asia), Canada (North America), China (Asia), and Brazil (South America). However, the total area of the United States, including Alaska and Hawaii, ranks third or fourth. Brazil is 166,000 square miles (431,000 km2) larger than the contiguous United States, but smaller than the entire United States, including Alaska, Hawaii, and overseas territories. The 2020 U.S. census population of the area was 328,571,074, comprising 99.13 percent of the nation's total population, and a density of 111.04 inhabitants/sq mi (42.872/km2), compared to 93.844/sq mi (36.233/km2) for the nation as a whole.

Other terms

While conterminous U.S. has the precise meaning of contiguous U.S. (both adjectives meaning "sharing a common boundary"), other terms commonly used to describe the 48 contiguous states have a greater degree of ambiguity.

Continental and mainland United States

Because Alaska is also a part of North America, the term continental United States also includes that state, so the term is qualified with the explicit inclusion of Alaska to resolve any ambiguity. On May 14, 1959, the United States Board on Geographic Names issued the following definitions based partially on the reference in the Alaska Omnibus Bill, which defined the continental United States as "the 49 States on the North American Continent and the District of Columbia..." The Board reaffirmed these definitions on May 13, 1999. However, even before Alaska became a state, it was properly included within the continental U.S. due to being an incorporated territory.

The term mainland United States is sometimes used synonymously with continental United States, but technically refers only to those parts of states connected to the landmass of North America, thereby excluding not only Hawaii and overseas insular areas, but also islands which are part of continental states but separated from the mainland, such as the Aleutian Islands (Alaska), San Juan Islands (Washington), the Channel Islands (California), the Keys (Florida), the barrier islands (Gulf and East Coast states), and Long Island (New York).

CONUS and OCONUS

CONUS, a technical term used by the U.S. Department of Defense, General Services Administration, NOAA/National Weather Service, and others, has been defined both as the continental United States and as the 48 contiguous states. The District of Columbia is not always specifically mentioned as being part of CONUS.

OCONUS is derived from CONUS with O for outside added, thus referring to Outside of Continental United States.

The lower 48

The term lower 48 is also used to refer to the conterminous United States. The National Geographic style guide recommends the use of contiguous or conterminous United States instead of lower 48 when the 48 states are meant, unless used in the context of Alaska. Almost all of Hawaii is south of the southernmost point of the conterminous United States in Florida.

Zone of the Interior

During World War II, the first four numbered Air Forces of the United States Army Air Forces (USAAF) were said to be assigned to the Zone of the Interior by the American military organizations of the time—the future states of Alaska and Hawaii, then each only organized incorporated territories of the Union, were respectively covered by the Eleventh Air Force and Seventh Air Force during the war.

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