The United States of America is a federal constitutional republic consisting of fifty states and a federal district. The country is situated mostly in central North America, where its forty-eight contiguous states lie between the Pacific and Atlantic Oceans, bordered by Canada to the north and Mexico to the south.
At 3.79 million square miles and with over 314 million people, the United States is the fourth-largest country by total area, and the third-largest by both land area and population.