WASHINGTON — Residents seeking to flee Houston by air before Hurricane Rita roars into town found only the costliest last-minute seats still available.

Continental Airlines on its Web site yesterday offered seats one way from Houston to Dulles International Airport for as much as $1,937. Searches of the travel Web sites SideStep and Orbitz turned up one-way and round-trip flights between Houston and the Washington area on various carriers from $300 to $624.

Airlines set aside only a certain number of cheap seats on each flight, and passengers rushing out of town gobbled them up. Many flights were sold out. Any last-minute tickets typically cost hundreds of dollars more than those bought a week or two in advance.

One last-minute, round-trip fare on Continental, Houston's dominant carrier, between Houston and Washington was $516. The same flight two weeks ago was selling for $228.

Adding to frustrations of travelers yesterday were long security lines at Houston's Bush Intercontinental Airport. Reports said some security screeners working for the Transportation Security Administration didn't show up for work. Many passengers with tickets faced waits of up to four hours in the crowded terminals.

Much of the chaos was the result of reduced work forces, officials said, as government and airline employees joined the mass evacuation. Others were late because of congested roads.

American Airlines said yesterday it was replacing four smaller, narrow-bodied planes with larger aircraft, two Boeing 777s and two Boeing 767s. The change added 360 seats out of Houston's Intercontinental Airport. Travel experts said those seats would not be discounted as a goodwill gesture.

"Airlines are not a social-service industry," said Terry Trippler, an analyst with cheapseats.com. "Everyone expects the airlines to take a financial hit, then criticizes them when they don't make money."

The airline industry is struggling through its worst financial crisis in history, with four major airlines — United, US Airways, Delta and Northwest — operating under bankruptcy-court protection.

Airline experts say it is unreasonable to expect the carriers to offer special fares as they battle to survive intense industry competition and soaring fuel prices.

Last-minute fares between Houston's Intercontinental Airport and Washington's Reagan National Airport were about $5 more than they were a month ago, largely because of a fuel surcharge put in place following Hurricane Katrina.

While airlines don't often lower prices during major catastrophes, most do allow passengers to change their existing tickets without paying a $50 to $100 change fee.

Airlines and airports aren't the only industries bracing for the hurricane. Some of the nation's largest hotel chains say many of their rooms are booked for miles outside of the city.

Information from The Dallas Morning News is included in

this report.