At the onset of the US Civil War in 1861, the nation was divided into slave states and free states. The slave states included Alabama, Arkansas, Florida, Georgia, Louisiana, Mississippi, North Carolina, South Carolina, Tennessee, Texas, and Virginia. Additionally, there were four border slave states that remained in the Union: Delaware, Kentucky, Maryland, and Missouri. These border states, while allowing slavery, did not join the Confederacy. On the other side, the free states consisted of California, Connecticut, Illinois, Indiana, Iowa, Maine, Massachusetts, Michigan, Minnesota, New Hampshire, New Jersey, New York, Ohio, Oregon, Pennsylvania, Rhode Island, Vermont, and Wisconsin. It's worth noting that West Virginia became a separate state in 1863 during the Civil War, breaking away from Virginia and joining the Union as a free state. This division between slave states and free states highlighted the deep-rooted conflict over slavery that led to the Civil War.