The United States of America -- commonly referred to as the United States, the US, the USA, the US of A, America, or the States -- is a constitutional federal democratic republic occupying a large part of the continent of North America. It borders Canada from the south and Mexico from the north in its main territorial area. It also contains, off the mainland, the Hawaiian islands of the Pacific Ocean and a large state northwest of Canada called Alaska that shares a sea border with the Russian Federation. In all, the country consists of fifty states, one state-neutral capital city called Washington, D.C. (for "District of Columbia"), and assorted smaller commonwealths and protectorates. It is so huge (third largest overall, behind Russia and Canada respectively), in fact, that it would take