The contiguous United States or officially the conterminous United States  consists of the 48 adjoining U.S. states (plus the District of Columbia) on the continent of North America.  The terms exclude the non-contiguous states of Alaska and Hawaii, and all other off-shore insular areas.   These differ from the related term continental United States which includes Alaska (also on the North American continent but separated from the 48 states by British Columbia, Canada) but excludes Hawaii and insular territories. 
The greatest distance (on a great circle route) entirely within the 48 contiguous states is 2,802 miles (4,509 km, between Florida and the State of Washington);  the greatest north-south line is 1,650 miles (2,660 km). 
Together, the 48 contiguous states and the District of Columbia occupy a combined 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 contiguous land, composing 83.65% of total U.S. land area, similar 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% of the nation's total water area.
The contiguous United States would be placed 5th in the list of sovereign states and dependencies by area; the total area of the country, including Alaska and Hawaii, ranks fourth. Brazil is the only country that is larger in total area than the contiguous United States, but smaller than the entire United States, while Russia, Canada and China are the only three countries larger than both. The 2010 census population of this area was 306,675,006, comprising 99.33% of the nation's population, and a density of 103.639 inhabitants/sq mi (40.015/km2), compared to 87.264/sq mi (33.692/km2) for the nation as a whole. 
The contiguous United States also does not include overseas U.S. territories such as American Samoa, U.S. Virgin Islands, Northern Mariana Islands, Guam and Puerto Rico, the latter of which has a higher population than Alaska and Hawaii.
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.
Because Alaska is also on the North American continent, the term continental United States would also include that state, so the term is qualified with the explicit inclusion of Alaska to resolve any ambiguity.     The term was in use prior to the admission of Alaska and Hawaii as states of the United States and at that time usually excluded outlying territories of the United States.   However, even before Alaska became a state, it was sometimes included within the "Continental U.S." 
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. 
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.  
During World War II, the first four numbered Air Forces of the 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 territories of the Union, were respectively covered by the Eleventh Air Force and Seventh Air Force during WW II.[ citation needed]
Both Alaskans and Hawaiians have unique labels for the contiguous United States because of their own locations relative to them.
Alaska became the 49th state of the United States on January 3, 1959. Alaska is on the northwest end of the North American continent, but separated from the rest of the United States Pacific coast by the Canadian province of British Columbia. In Alaska, given the ambiguity surrounding the usage of continental, the term "continental United States" is almost unheard of when referring to the contiguous 48 states. Several other terms have been used over the years. The term Lower 48 has, for many years, been a common Alaskan equivalent for "contiguous United States";   today, more Alaskans use the term "Outside",   though a few persons may use "Outside" to refer to any location not within Alaska. 
Hawaii became the 50th state of the United States on August 21, 1959. It is the southernmost and so far, the latest state to join the Union. Not part of any continent, Hawaii is located in the Pacific Ocean, about 2,200 miles (3,500 km) from North America and almost halfway to Asia. In Hawaii and overseas American territories, for instance, the terms the Mainland or U.S. Mainland are often used to refer to the contiguous United States. 
Apart from off-shore US islands, a few continental portions of the contiguous US are accessible by road only by traveling through Canada. Point Roberts, Washington; Elm Point, Minnesota; and the Northwest Angle in Minnesota are three such places. Alburgh, Vermont, is not directly connected by land, but is accessible by road via bridges from within Vermont and from New York. 
The 48 contiguous United States are:
- New Hampshire
- New Jersey
- New Mexico
- New York
- North Carolina
- North Dakota
- Rhode Island
- South Carolina
- South Dakota
- West Virginia
- "What constitutes the United States, what are the official definitions?". www.usgs.gov.
"United Airlines website". Archived from
the original on April 2, 2012. Retrieved April 4, 2012.
Contiguous United States: The 48 adjoining states and the District of Columbia.
- Random House (1991). Random House Webster's College Dictionary. New York: Random House. ISBN 0-679-40110-5.
- These maps show the contiguous 48 states and D.C., but not Alaska and Hawaii.
- "Military Bases in the Contiguous United States". National Park Service, U.S. Department of the Interior. Retrieved November 28, 2012.
- "Soil Moisture Regimes of the Contiguous United States". U.S. Department of Agriculture. Retrieved November 28, 2012.
- "The Longest Line in America!". Retrieved October 15, 2013.
- "HowStuffWorks "Geography of the United States - Geography"". Geography.howstuffworks.com. March 30, 2008. Retrieved October 29, 2013.
- "The World Factbook". cia.gov.
- "Resident Population Data - 2010 Census". United States Census Bureau. Archived from the original on October 28, 2011. Retrieved January 30, 2011.
"National Geographic Style Manual". Retrieved April 4, 2012.
The continental United States comprises the 48 contiguous, or coterminous, states plus Alaska.
"United Cargo website". Archived from
the original on April 2, 2012. Retrieved April 4, 2012.
Continental United States: The 48 adjoining states, Alaska and District of Columbia.
"Alaska Airlines website". Retrieved April 4, 2012.
The Continental U.S. includes the lower 48 states as well as the State of Alaska, unless otherwise specified.
- Rodda, William H (1949).
Inland Marine and Transportation Insurance. Retrieved April 4, 2012.
In the absence of any such statement, Alaska probably would be regarded as a part of the continental United States.(before statehood)
- "United Cargo website". Archived from the original on April 2, 2012. Retrieved April 4, 2012.
"U.S. Navy Style Guide". Retrieved April 4, 2012.
CONUS - "Continental United States" CONUS refers to the 48 contiguous states.
- Law, C.C.H. Tax (2007).
Internal Revenue Code.
9780808015963. Archived from
the original on October 16, 2015.
the term "United States mainland" means the continental United States (not including Alaska).
"Abstract of the 1900 Census (1904), p.xiii" (PDF).
The area ... is continental United States, by which is meant that part of the United States lying on the continent of North America south of the Canadian boundary. It thus excludes Alaska and the recent insular accessions of Hawaii, Porto Rico (sic), the Philippine Islands, Guam, Samoa...
- "... merchandise to foreign countries from continental United states, Puerto Rico, and the territories of Alaska and Hawaii." United States Foreign Trade (1950-1953)
- "In the absence of any such statement, Alaska probably would be regarded as a part of the continental United States." Inland Marine and Transportation Insurance (1949)
- "Per Diem Rates (CONUS and OCONUS)". United States General Services Administration.
"U.S. Navy Style Guide".
CONUS - "Continental United States." CONUS refers to the 48 contiguous states. It is not synonymous with United States. CONUS is acceptable on first reference."CONUS" seems to be used primarily by the American military and the Federal government and those doing business with them.
"Glossary of Army Terms". Retrieved April 4, 2012.
"OCONUS: Outside Continental United States
"National Geographic Style Manual: conterminous, or contiguous, continental, continental United States". Retrieved April 4, 2012.
Use contiguous, or conterminous, for the 48 states. The continental United States comprises the 48 contiguous, or conterminous, states plus Alaska.
"National Geographic Style Manual: Alaska". Retrieved December 6, 2013.
The continental United States includes Alaska. In Alaska context, lower forty-eight or lower 48 may be used. Do not hyphenate lower 48 as an adjective. The term outside may be put in quotes on first reference if ambiguous. To distinguish the 48 states from the 49 or 50, use contiguous or conterminous.
- "Learn to Speak Alaskan - Alaskan Language Tips - Princess Lodges". princesslodges.com.
- "ALASKA: State Profile". Archived from the original on January 26, 2010. Retrieved December 6, 2013.
- "Ski". google.com.
- "What are some things Alaska does differently from the contiguous states? - Quora". quora.com.
- Journal, Copper River Country. "Speaking Alaskan: Words Alaskans Say".
- Edles, Laura Desfor (2003). "'Race,' 'Ethnicity,' and 'Culture' in Hawai'i: The Myth of the 'Model Minority' State". In Loretta I. Winters and Herman L. DeBose (ed.) New Faces in a Changing America: Multiracial Identity in the 21st Century. SAGE Publications. p. 241. ISBN 9780761923008.
- Ross, Oakland (June 3, 2011). "Orphans of the atlas". Toronto Star. Retrieved June 5, 2011.
|Wikivoyage has a travel guide for Contiguous United States.|