Airlines planned to resume flights in and out of East Coast airports Monday after they were shut down over the weekend by Tropical Storm Irene.

The quicker airlines get back in the air, the less the inconvenience on travelers whose flights were scrubbed by the storm. More than 9,000 flights had been canceled by Sunday, according to flight-tracking services.

Irene was downgraded from a hurricane Sunday as winds ebbed around the time that the storm pushed into New York, the nation's busiest air-traffic region.

Federal officials said airports reopened around Washington, which took a glancing blow from Irene. American Airlines said it was resuming flights at the three major airports around the capital.

Officials say the 3 major NYC-area airports to reopen Monday morning for most flights. United, Continental, Delta and JetBlue said they planned to resume service there and in Boston on Monday.

The longer that the New York area's Kennedy, LaGuardia and Newark, N.J., airports are shuttered, the worse it will be as travel delays ripple across the country. Airline and federal officials said they didn't know when the airports would reopen, noting that mass transit in New York remained shut down, making it difficult for airport employees and passengers to reach the airports.

"It's really dependent upon mass transit and the airport being ready to support the start-up," JetBlue CEO Dave Barger told NBC.

Airlines said passengers should call ahead and make sure they have a confirmed seat before going to the airport.

FlightAware, which tracks delays and cancelations, said airlines had indicated about 500 cancelations for Monday, said the service's CEO, Daniel Baker. That would be a very small percentage of the nation's flights.

Airlines have already canceled more than 9,000 flights since Irene came ashore at North Carolina on Saturday, according to FlightAware. United, Continental, Delta, American, Southwest and JetBlue canceled all Sunday flights in the New York and Philadelphia areas long before Irene hit. They also moved planes out of the storm's path to avoid damage, further slowing the recovery of normal service.

Many planes have been full this summer, so finding empty seats for passengers whose first flight was canceled could be difficult. When blizzards hit the same region in December and February, it took some passengers days to get home.

Sara Hesselsweet of Norwalk, Conn., was scheduled on a Sunday flight home from vacation at Lake Tahoe on the California-Nevada border. After the flight was canceled, American Airlines told Hesselsweet it couldn't find seats for her, her husband and 2-year-old son until next Saturday.

The family decided to fly from Reno, Nev., to Dallas and on to Chicago on Sunday, then rent a car and drive back to Connecticut.

"We checked Philadelphia, D.C., Boston, the Carolinas -- we couldn't get a flight anywhere," said Hesselsweet, sitting amid a pile of carry-on bags in the Reno airport.

The storm affected other forms of transportation too. Amtrak canceled many passenger trains, Greyhound scrubbed trips between Washington and New York, and cruise lines changed some of their itineraries as Irene made its way from the Bahamas to the Northeast.