About the United States or the United States of America (USA), commonly referred to as the United States (US) or America, is a federal republic consisting of 50 states and a federal district. The 48 contiguous states and Washington, D.C., lie in the middle of North America between Canada and Mexico. It ranked 3rd for size and population. The official language is English and is spoken by 80% of the population. About 82% of the American population lives in cities.