Antebellum South Carolina is typically defined by historians as South Carolina during the period between the War of 1812, which ended in 1815, and the American Civil War, which began in 1861. After the invention of the cotton gin in 1793, the economies of the Upcountry and the Lowcountry of the state became fairly equal in wealth. The expansion of cotton cultivation upstate led to a marked increase in the labor demand, with a concomitant rise in the slave trade. The trans-Atlantic slave trade, or international buying and selling of slaves, was outlawed by the United States in 1808, as of which date South Carolina was the only state that had not already prohibited the importation of slaves. After that date there was a burgeoning domestic or internal, national slave trade in the U.S.