The Department of Transportation released data Monday ranking 29 major airports across the country for their arrivals and departures for the month of July.
O'Hare had the worst on-time performance for departing flights of all major airports. Only about 69 percent of flights departed on time.
Midway came in 19th place, with more than 76 percent departing on schedule.
O'Hare performed better in July for on-time arrivals, with more than 71 percent of flights arriving on time.
Midway again did better, though, with 85 percent of flights there coming in on schedule.