DALLAS - American Airlines resumed most of its flights today after a computer glitch forced the airline to ground all flights yesterday.

But some cancellations persisted, and delays were still common. About a third of American flights were late as of mid-afternoon.

American and subsidiary American Eagle canceled more than 300 flights by mid-afternoon, according to the flight-tracking service FlightAware.com. American said some flights were affected by bad weather in Chicago.

To help with the remaining delays, American added seven unscheduled flights to accommodate passengers stranded the day before in Chicago, Dallas and Los Angeles.

On Tuesday, American and American Eagle canceled nearly 1,000 flights and delayed another 1,100. Two-thirds of their scheduled flights were late or never got into the air.

American's CEO blamed Tuesday's breakdown on a software problem that knocked out computer systems needed for booking flights, tracking bags, loading and fueling planes and more.

AP wire services were used in this report.