It happened near the Granville station just after 3 o'clock Sunday afternoon.
That stopped trains running between Granville and Howard stations.
No one was injured.
"The best way to remove the passengers was to cut the two cars in front, and keep the passengers on that side of the derailed car, and take that train into Granville station. And too that car into Howard Street," said Chicago Police Chief Lynda Turner.
Shuttle buses are moving passengers between Wilson and Howard. CTA expects to have service running back to normal late Sunday night.