In the waning days of the war, which ran from 1861 to 1865, the Congress approved an amendment to abolish slavery in all of the United States. Slavery was an institution in America in the 18th and 19th centuries. The Southern states, with their agricultural economies, relied on the slavery system to ensure the cash crops (cotton, hemp, rice, indigo, and tobacco, primarily) were tended and cultivated. Slaves were not unknown in the North, but abolition in the North was completed by the 1830's. In 1808, the Congress prohibited the slave trade, not a year later than allowed in the Constitution. A series of compromises, laws, acts, and bills tried to keep the balance between the slave states and the non-slave states. South Carolina voted to secede from the United States as a result of Abraham Lincoln's election to the Presidency. Lincoln had, over time, voiced strong objections to slavery, and his incoming administration was viewed as a threat to the right of the states to keep their institutions, particularly that of slavery, the business of the states.