Uncle Sam's home is America, which is a seven letter word, and USA, which is a three letter acronym. America is the name of the country located in North America, bordered by Canada to the north and Mexico to the south. It is the world's third-largest country by total area and has the world's largest economy. The United States of America, commonly referred to as the United States or simply America, is a federal republic composed of 50 states, a federal district, five major self-governing territories, and various possessions.