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United States

In both legends and text, spell out on first use; after that U.S. is acceptable. United States is preferred to America and American as both noun and adjective:
            chief United States export.

Possessive form is United States'. Use contiguous or conterminous for the 48 states. The continental United States comprises the 48 plus Alaska. In Alaskan context, lower forty-eight may be used.

For the proper appellation for a citizen of a particular state, consult the "Geographical Names'' section of Webster's, with exceptions entered in this manual.

Abbreviations:

U.S., U.S.A.
USA
USAF
USN

United States Army
United States Air Force
United States Navy
USMC
USNR
USCG
USGS
U.S.S.
United States Marine Corps
United States Naval Reserve
United States Coast Guard
United States Geological Survey
United States Ship
See also federal, government, nation, and state.