The United States of America is many things. It is the world's most powerful country, and one of the largest. It has a history of political revolution and social progress, as well as a legacy of slavery and genocide. In one sense, mapping the United States should be a simple matter of displaying borders and geography. But America is a complex nation with a long and fascinating history that could never be captured in a single frame. Here's a glance at America's past and present, in 70 maps.