Watch Frozen: State Of The South on CNN at 11 p.m. ET Wednesday.
(CNN) -- While airports across the southeastern United States continued to dig out from Tuesday's snowstorm, Wednesday turned into a long day of cancellations and delays for frustrated travelers.
Airlines had canceled more than 2,200 U.S. flights by Wednesday at 5 p.m. ET according to flight tracking site FlightAware.com. That follows about 3,200 flight cancellations on Tuesday.
The airport most affected was Hartsfield-Jackson Atlanta International, the world's busiest, with more than 1,000 flights canceled, according to FlightAware.com. Delta Air Lines, which is based in Atlanta, was affected most.
"This spate of winter weather has hit a lot of airports that usually don't face winter weather and are less prepared for it," Mark Duell, FlightAware's vice president of operations, said via e-mail. "When every flight needs de-icing, (those airports) see a massive slowdown in departures, and the airlines pre-emptively cancel flights."
Many airports struggled all day to return to normal operations.
Flights arriving in Atlanta were facing delays of more than five hours as of 5 p.m. ET, according to the Federal Aviation Administration. That's because Delta requested a ground stop, driven by the weather and airport access difficulty, which was later converted into a ground delay program, spokesman Morgan Durrant said via e-mail. "This means that flights bound to ATL from other airports are seeing delays." Check fly.faa.gov for the most current information on delays.
With more than 900 Atlanta flights canceled Tuesday, some passengers intending to depart Atlanta stayed at the airport overnight, airport spokesman Reese McCranie said. On Wednesday by 5 p.m. ET, airlines had canceled more than 1,000 flights departing from or arriving at the Atlanta airport, according to FlightAware.com.
Delta reported about 1,200 cancellations systemwide by 3:30 p.m. on Wednesday, on top of 1,200 Tuesday cancellations, said Delta's Durrant. And the airline is still facing challenges getting employees to work at its Atlanta hub, he said.
"Last night, we did allow airport employees to sleep aboard aircraft parked at gates and we flew an extra section (unscheduled flight) full of pilots and flight attendants to Louisville so they could be afforded rest in hotel rooms," Durrant said via e-mail. "This group was scheduled to have hotel stays near ATL as part of their regularly scheduled trips."
Alabama's Birmingham-Shuttlesworth International Airport shut down flight operations Tuesday afternoon as the snowfall began, and "crews worked overnight and continue to work this morning to clear the (two) runways," wrote airport spokeswoman Toni Herrera-Bast. One runway had reopened by midday Wednesday.
Southwest Airlines and AirTran canceled more than 300 of 3,600 scheduled flights Wednesday. The combined airline canceled nearly 400 flights Tuesday.
"Our people in Atlanta, in particular, are facing a challenging day," said Southwest spokesman Brad Hawkins via e-mail Wednesday morning. "What you're seeing there in Atlanta is a continuing operation but an extremely slow operation, resulting in just a few departures every hour."
U.S. Airways, which merged with American but still operates separate flights, canceled more than 200 flights Wednesday, on top of 300 cancellations Tuesday, said spokesman Davien Anderson.
While the Charlotte, North Carolina, airport reported no major delays in arrivals or departures Wednesday, with all runways free of ice and snow, U.S. Airways was still hit hard.
"Our employees are working hard to get operations back to normal in Charlotte," Anderson said via e-mail. "We hope to return to normal operations by tomorrow."
CNN's Etan Horowitz reported from Tampa, Florida.