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.^{[3][11][12][13]} 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.^[1] However, even before Alaska became a state, it was properly included within the continental U.S. due to being an incorporated territory.^[14]

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).^[15]

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.^[16][17] The District of Columbia is not always specifically mentioned as being part of CONUS.^[17]

OCONUS is derived from CONUS with O for outside added, thus referring to Outside of Continental United States.^[16][18]

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.^[5][19] 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.^{[citation needed]}

Alaska

The vast territory of Alaska became the 49th state of the United States on January 3, 1959.^[20] Alaska is the northwest extremity of the North American continent, separated from the U.S. West Coast by the Canadian province of British Columbia. The term Lower 48 has, for many years, been a common Alaskan equivalent for "contiguous United States";^[21][22] some Alaskans may use the term Outside for those states, though some may use Outside to refer to any location not within Alaska.^[23]

Hawaii

The territory of Hawaii, consisting of the entire Hawaiian Islands archipelago except for Midway Atoll,^[a] became the 50th state of the United States on August 21, 1959. It is the southernmost U.S. state, and the latest one to join the Union. Not part of any continent, Hawaii is located in the Pacific Ocean, about 2,200 miles (3,541 km) from North America and almost halfway between North America and Asia. In Hawaii and overseas American territories, for instance, the terms the Mainland or U.S. Mainland are often used to refer to the 49 states in North America.^[24][25]

Puerto Rico

Puerto Rico is an unincorporated territory of the United States located in the northeast Caribbean Sea, approximately 1,000 miles (1,609 km) southeast of Miami, Florida. Puerto Ricans born in Puerto Rico are U.S. citizens and are free to move to the mainland United States. The term Stateside Puerto Rican refers to residents of any U.S. state or the District of Columbia who were born in, or can trace their family ancestry to, Puerto Rico.^[26]

U.S. Virgin Islands

The U.S. Virgin Islands is a U.S. territory located directly to the east of Puerto Rico in the Caribbean Sea.^[27] The term stateside is used to refer to the mainland, in relation to the U.S. Virgin Islands^[28] (see Stateside Virgin Islands Americans).

American Samoa

American Samoa is a U.S. territory located in the South Pacific Ocean in Polynesia, south of the equator — it is 2,200 miles (3,500 km) southwest of Hawaii.^[29] In American Samoa, the contiguous United States is called the "mainland United States" or "the states"; those not from American Samoa are called palagi (outsiders).^[30]