By 1840, nearly 7 million Americans–40 percent of the nation’s population–lived in the trans-Appalachian West. Following a trail blazed by Lewis and Clark, most of these peopl… See more

Meanwhile, the question of whether or not slavery would be allowed in the new western states shadowed every conversation about the frontier. In 1820, the Missouri C… See more

In 1848, the Treaty of Guadelupe Hidalgo ended the Mexican War and added more than 1 million square miles, an area larger than the Louisiana Purchase, to the United States. Th… See more

But the larger question remained unanswered. In 1854, Illinois Senator Stephen A. Douglas proposed that two new states, Kansas and Nebraska, be establishe… See more