The United States is contiguous 48 U.S. states in the North American continent is southern Canada and northern Mexico, plus the District of Columbia. This term does not include the state of Alaska and Hawaii, and all offshore U.S. territories and possessions, such as Puerto Rico.
Together, the 48 contiguous states and DC occupies a combined area of 3,119,884.69 square miles (8,080,464.3 km2). Of this amount, 2,959,064.44 square miles (7,663,941.7 km2) is land, comprising 83.65% of U.S. land area. Officially, 160,820.25 square miles (416,522.5 km2) is an area of water, comprising 62.66% of the nation's water. Its 2000 census population was 279,583,437, comprising 99.35% of the national population. The density of population is 94.484 people / sq mi (36.480/km ²), compared with 79.555/sq miles (30.716/km ²) for the nation as a whole. 2010 census population was 306,675,006, comprising 99.33% of the nation's population, and population density of 103.639 / sq mi (40.015/km ²), compared with 87.264/sq miles (33.692/km ²) for the nation as a whole.
Other things
While the U.S. borders and U.S. borders have the exact same meaning to the contiguous United States (third adjective meaning "sharing a common boundary"), another term commonly used to describe the 48 contiguous states have a greater degree of ambiguity.
Continental United States
Because Alaska is also on the continent of North America, the term continental United States, if interpreted literally, would also cover country, so the term is sometimes qualified with the explicit inclusion or exclusion of Alaska to resolve the ambiguity. This term has been used before the adoption of Alaska and Hawaii as states of the United States, and at that time usually spent USHowever remote areas, even before Alaska became a state, it is sometimes included in the "Continental U.S.".
CONUS / OCONUS
CONUS, a technical term used by the U.S. Department of Defense and the General Services Administration, has been defined either as the continental United States, and the 48 contiguous states. District of Columbia is not always specifically mentioned as part of the CONUS.
From CONUS to OCONUS O for external add, thus referring Outside Contiguous United States (OCONUS).
The lower 48
The lower run 48 may or may not include the District of Columbia (which is not part of one of 48 countries). National Geographic style guide recommends the use of the United States adjacent or not adjacent to the lower 48 when 48 countries are intended, except in the context of Alaska. If not avoided as a misnomer, because all the big island of Hawaii is farther south than the southernmost point of continental countries.
The term is used in non-contiguous states
Both Alaska and Hawaii have their own unique label for the contiguous United States due to their location relative to their own.
Alaska
Main article: Outside (Alaska)
Alaska became the 49th state of the United States on January 3, 1959. Alaska is on the northwest tip of the North American continent, but is separated from the rest of the United States by the province of British Columbia in Canada. In Alaska, given the ambiguity surrounding the use of the continent, the term "continental United States" is almost unheard of when referring to the 48 contiguous states. Several other terms have been used for many years. The 48 is the lower term for years, and still is, Alaska is the most common equivalent to "contiguous United States."
Hawaii
Hawaii became the 50th country to the United States on August 21, 1959. Hawaiian Islands are located in Oceania, and about 2,200 miles (3,500 km) from the North American continent. In Hawaii and U.S. territories abroad, for example, the term or the mainland U.S. mainland is used to refer to the continental United States.
