Originally Posted by
CPS89
Plenty of time to see downtown, but I'd strongly recommend taking Uber over the blue line. They're still forcing people to switch trains at Rosemont at certain times of the day. Uber is usually $30-40 each way.
Keep an eye on traffic, it can take 1-1.5hrs to go from downtown to ORD if it's backed up.
And if taking the Blue line and having to hoof it around stations, then between the heat, humidity and rainstorms, there can be the following unpleasantness of being quite sweaty or otherwise wet before taking the flight out of ORD. If having access to a shower at the lounge or an ORD area gym/hotel, then that may be less of an issue.