At the close of the eighteenth century, the landscape of the British colonies had changed dramatically. Politically, these were no longer separate colonies but states united in a national republic whose constitution had been ratified twelve years before. The disparate colonies had banded together in 1776 to declare themselves independent of British colonial authority, and after eight years of warfare that independence had been recognized by Great Britain. Economically, the nation of agriculture and commerce began to explore the promising possibilities of industrial production. Geographically, the settlement frontier continued to move west at an extraordinary pace, opening opportunities for settlers and igniting more conflicts with native Americans. By 1800, the nation of thirteen states had become sixteen, including not only another New England state, Vermont, but the western states Kentucky and Tennessee. By 1820, the nation had twenty-four states, industrialization had taken hold, the frontier approached the Mississippi River, and, within the decade, native Americans east of the Mississippi faced removal from their homelands. As the nation expanded, the intoxicating independence, moving frontier, and republican politics combined to transform society, culture, and religion.