After the War of 1812, Americans settled the Great Lakes region rapidly thanks in part to aggressive land sales by the federal government. Selling federal lands, mostly ceded by American Indians, was a major source of revenue in the era and officials were eager to survey and sell large parcels for new settlers. Missouri’s admission as a slave state presented the first major crisis over westward migration and American expansion in the antebellum period. Farther north, lead and iron ore mining spurred development in Wisconsin. By the 1830s and 1840s, increasing numbers of German and Scandinavian immigrants joined easterners in settling the Upper Mississippi watershed. Little settlement occurred west of Missouri as migrants viewed the Great Plains as a barrier to farming, the Rocky Mountains as undesirable to all but fur traders, and local American Indians as too powerful to allow white expansion.

“Do not lounge in the cities!” commanded publisher Horace Greeley in 1841, “There is room and health in the country, away from the crowds of idlers and imbeciles. Go west, before you are fitted for no life but that of the factory.” The New York Tribune often argued that American exceptionalism required the United States to benevolently conquer the continent. However, the vast west was not empty. Native Americans controlled much of the land east of the Mississippi River and almost all the west. Expansion hinged on a federal policy of Indian removal.