Since the early nineteenth century, Americans had looked to western lands for economic opportunities. In the north, the transportation revolution had made the Midwest accessible for commercial farmers. In the South, the introduction of the cotton gin had made short-staple cotton an attractive plantation crop and revived the institution of slavery. Buying their slave labor from retiring Virginia tobacco growers, entrepreneurial planters brought new southern lands into cotton cultivation all the way to and along the Mississippi River. In 1819, Americans’ first experience with the volatility of a national market economy highlighted the significance of land ownership for economic stability. At the same time, the Missouri Compromise established a political pact on the admission of free and slave states and removed the most important obstacle to western expansion— political deadlock.