In the southern states of the United States it was legal to own people if their skin color was black. I'm not making this up.

Wikipedia - Abraham Lincoln and slavery

Abraham Lincoln's position on slavery is one of the most discussed aspects of his life. Lincoln often expressed moral opposition to slavery in public and private. "If slavery is not wrong, nothing is wrong", he stated in a now-famous quote. "I can not remember when I did not so think, and feel." However, the question of what to do about it and how to end it given that it was so firmly embedded in the nation's constitutional framework and in the economy of much of the country was complex and politically challenging.

As early as the 1850s, Lincoln was attacked as an abolitionist. But while many abolitionists emphasized the sinfulness of individual owners, Lincoln did not. Lincoln was married to Mary Todd Lincoln, the daughter of a slaveowner from Kentucky. While William Lloyd Garrison in The Liberator newspaper, and a small but growing group of abolitionists called for total, immediate abolition of slavery ("immediatism"), Lincoln instead focused on the goal of preventing the creation of new slave states and specifically blocking the expansion of slavery into the new Western territories. Lincoln's 1850s activism on that issue started in reaction to the 1854 Kansas–Nebraska Act, designed by his great rival, Illinois Senator Stephen A. Douglas. The Act allowed settlers to decide on slavery in their territories. Lincoln worried that the extension of slavery into new western lands could block free labor on free soil when rich slaveowners bought up all the best lands.

Lincoln, with partial compensation to owners, ended slavery in the District of Columbia in 1862; the abolitionist goal became possible after decades with the departure of the southern members of Congress at the beginning of the American Civil War. In 1861 and 1862, Lincoln tried unsuccessfully to get the loyal border states of Delaware, Kentucky, Maryland and Missouri to do likewise. He repeatedly stated that his goal was the preservation of the Union, not to end slavery in the states in which it existed but throughout the war he encouraged states to abolish slavery, and state abolition plans were adopted in Maryland, Missouri, West Virginia, Tennessee, Louisiana, and Arkansas before the end of the war.

In a highly-significant shift, Lincoln used his role as commander-in-chief to issue the Emancipation Proclamation, effective January 1, 1863. Under the guise of a military measure, it made all slaves in Confederate areas forever free under US law as soon as the US Army reached them, which was completed by June 1865. On its first day, the proclamation freed tens of thousands of slaves. Week by week, as the Union army advanced, slaves were liberated. The last were freed in Texas on "Juneteenth" (June 19, 1865). The final abolition in the border states was achieved later that year by the ratification of the Thirteenth Amendment, which Lincoln had vigorously promoted.