The July numbers for 29 major airports were released Monday.
At O'Hare, about 76 percent of its flights landed on time. That put O'Hare at No. 18.
Midway was ranked 11th with 79 percent arriving on schedule.
With 74 percent on time for departures, O'Hare is ranked at 19th in the country.
Midway was last with just 68 percent leaving on time.