Slavery expanded greatly in the 19th century American South as the cotton industry boomed. Over 1 million slaves were forcibly relocated from the upper South to the deep South states between 1820 and 1860. Though conditions for slaves varied, they were all denied freedom. Slaves resisted through slow work, sabotage, and occasional revolts like Nat Turner's rebellion in 1831. The Missouri Compromise of 1820 attempted to balance the number of slave and free states admitted to the union.