a republic in the N Western Hemisphere comprising 48 conterminous states, the District of Columbia, and Alaska in North America, and Hawaii in the N Pacific. 226,545,805; conterminous United States, 3,022,387 sq. mi. (7,827,982 sq. km); with Alaska and Hawaii, 3,615,122 sq. mi. (9,363,166 sq. km). Cap.: Washington, D.C. Abbr.: U.S., US Also called United States of America, America.