More than half a dozen airports in and around Houston, including one of the nation’s busiest aviation hubs, remained closed Monday amid catastrophic flooding and rainfall associated with Tropical Storm Harvey.

Houston’s major airports — George Bush Intercontinental, the city’s largest, and William P. Hobby Airport — are expected to remain closed until Wednesday, the Federal Aviation Administration said Monday morning in an air traffic report. Later Monday, United Airlines said George Bush Intercontinental would be closed until at least Thursday. Roads are flooded throughout Houston, and thousands of flights have been canceled. Airlines are offering waivers to passengers, allowing them to reschedule their flights into September.

More than 54 million passengers made their way through the Houston Airport System last year. Most of them came through George Bush Intercontinental, which has flights to more than 70 international destinations and to more destinations in Mexico than any other U.S. airport.

The airport had just over 16 inches of rain Sunday, doubling the previous record of more than 8 inches set in 1945, according to the National Weather Service forecast office in Houston/Galveston. William P. Hobby Airport serves far fewer people (about 13 million last year), but offers nonstop flights to dozens of destinations in the United States, Mexico, Latin America and the Caribbean, and is one of Southwest Airlines’ most active hubs.

The carrier issued a travel advisory asking people not to attempt to reach Hobby Airport.

Together the airports support more than 220,000 local jobs, injecting more than $26 billion to the local economy, according to the Houston Airport System. George Bush Intercontinental is one of the largest hubs for United Airlines, which employs more than 11,000 people in the areas affected by Tropical Storm Harvey.

Thousands of flights have been canceled on United, Southwest and other airlines throughout the weekend and into Monday, according to FlightAware.