The United States changed dramatically in its first half century. In 1776 the U.S. consisted of THIRTEEN COLONIES clustered together on the eastern seaboard. By 1821 eleven new states had been added from Maine to Louisiana. This geographic growth and especially the political incorporation of the new states demonstrated that the United States had resolved a fundamental question about how to expand. This growth not only built upon the Louisiana Purchase, but included military intervention in SPANISH FLORIDA which the United States then claimed by treaty in 1819.