The United States is a global superpower. With fifty states and sixteen territories, the US is the worldÎs fourth largest country. More than 331 million people call the US home. Learn more about the US from its first peoples to its presidents. Discover the nationÎs three branches of government. Then uncover the USÎs challenges from climate change to becoming a fairer country. The USÎs decisions on these topics will impact the rest of the world.