The United States of America (also referred to as the United States, the U.S., the USA, the States, or America) is a federal constitutional republic comprising fifty states and a federal district. The country is situated mostly in central North America, where its forty-eight contiguous states and Washington, D.C. the capital city, lie between the Pacific and Atlantic Oceans. The state of Alaska is in the northwest of the continent, with Canada to the east. The state of Hawaii is an archipelago in the mid-Pacific.