STEPHEN FRAZIER, CNN ANCHOR: The Chicago Historical Society is now the proud owner of a letter written by President Abraham Lincoln, and it's an important letter which played a significant role in ending slavery in the United States. CNN's Keith Oppenheim explains.</s>KEITH OPPENHEIM, CNN CORRESPONDENT (voice-over): On the streets of Chicago, people of different races and backgrounds walk freely, most likely unaware something in this building, the Chicago Historical Society, represents the freedoms they enjoy today. It's a letter signed by Abraham Lincoln; a rather brief note that directs the secretary of state to put the seal of the United States on the Emancipation Proclamation, thereby freeing the slaves in the rebellion states.</s>LONNIE BUNCH, PRESIDENT, CHICAGO HISTORICAL SOCIETY: The way it let people know that Abraham Lincoln was clearly putting his legacy on the line by saying that, ultimately, slavery will end in the United States.</s>OPPENHEIM (on camera): Keep in mind, this is not the Emancipation Proclamation itself. Lincoln had already written that. This document gave the proclamation legal power. The Chicago Historical Society recently paid $800,000 for this at auction, and the feeling here was this letter, held in private hands for decades, should be made available for viewing by the public. (voice-over): Some history gives this letter some context. Lincoln was elected based on his vow to preserve the union, not to end slavery. But by the middle of the Civil War, the politics had changed and Lincoln began to believe the North needed more of a galvanizing cause. This letter, signed January 1, 1863, represented a turning point in American history when not just a union, but also equality, became an official focus of the Civil War.</s>RUSSELL LEWIS, CHICAGO HISTORICAL SOCIETY: You would never think that something, you know, so brief like that would have such a momentous and powerful impact. But, in fact, in signing that he made it a law, and there was no turning back.</s>OPPENHEIM: In Chicago, I'm Keith Oppenheim reporting.
Chicago Historical Society Purchases Letter by Lincoln