United States of America or United States, popularly referred to as the United States or as America, a federal republic on the continent of North America, consisting of 48 contiguous states and the non-contiguous states of Alaska and Hawaii. Outlying areas include Puerto Rico, American Samoa, Guam, and the US Virgin Islands. The conterminous 48 states are bounded on the north by Canada, on the east by the Atlantic Ocean, on the south by the Gulf of Mexico and Mexico, and on the west by the Pacific Ocean. The northern boundary is partly formed by the Great Lakes and the St Lawrence River; the southern boundary is partly formed by the Rio Grande. New York is the largest city in the United States. Washington, D.C., is the capital.