Abraham Lincoln officially became the 16th President of the United States on March 14, 1861. He was elected to that position on November 6th, 1860.
Lincoln began his second term of office on March 4, 1865. His election spurred states in the southeastern United States to secede, for they feared that he and his party would act to reduce or end slavery. On December 20, 1860, four months before Lincoln took office, South Carolina seceded, followed in early February by Georgia, Florida, Mississippi, Alabama, Louisiana and Texas. The seceding states formed a new government, the Confederate States of America. Within two months, Lincoln was president and the Civil War had begun.