Minutes to Circle

If you’ve ever driven from O’Hare into the heart of Chicago, you have surely seen the electric signs that say things like “24 minutes to circle via Kennedy.” I’ve always thought that was bizarre at best, since I am aware of the Loop in Chicago, but not anything known as “the circle.” Can anybody shed light on this? Is it just a huge mistake, possibly by highway workers who don’t know the city, like when I once had to call 911 and the dispatcher didn’t believe that Lake Shore Drive is in Chicago? [Yes, that really happened – she insisted I must somehow be calling from Indiana. She also did not recognize as a Chicago landmark the term “I-55.”]