Reinforced armies of federal search teams, medics and National Guard troops began fanning out into wind-whipped and waterlogged southwestern Louisiana and coastal Texas yesterday, racing to prove the government had learned from its disastrous missteps earlier this month on the Gulf Coast.

And while yesterday's early assessments were positive -- with few reports of unanswered calls for help or broad communication breakdowns that crippled the response to Hurricane Katrina -- officials acknowledged that Hurricane Rita had not presented the ultimate test for which they had prepared.

Hurricane Katrina "was so much more massive. Most people still don't understand that," said Michael Lowder, deputy director of response operations at the Federal Emergency Management Agency headquarters in Washington. In New Orleans, the levees failed, "then you had the civil unrest piece of it. That was something that was not planned for, not anticipated. . . . That affects the whole response."

Although floodwater was still rising yesterday in some low-lying towns and wind restricted damage-assessment flights, state and federal authorities cautiously projected confidence in their ability to respond to the storm in coming days, at least partly because it was far less damaging. President Bush, who visited the Texas emergency command center in Austin, praised government agencies as "well-organized and well-prepared to deal with Rita."

Officials also attributed their success to the sometimes chaotic evacuation of 3 million people from Houston and other cities, an exodus left incomplete in New Orleans before Hurricane Katrina hit Aug. 29.

"The damage is not as severe as we had expected it to be," FEMA Acting Director R. David Paulison said in Washington, despite swamped roads, failed bridges and extensive structural damage across several cities and southwest Louisiana. "Every mayor that we have talked to is crediting the evacuations with the fact we have no reported deaths at this time."

Texas and Louisiana leaders said yesterday's relative calm reflected greater preparation and cooperation at all levels.

"We learned a great deal from Katrina that was put in place in Texas," Sen. Kay Bailey Hutchison (R-Tex.) said in Austin at a news conference with Gov. Rick Perry (R).

"We are all working together as a team," Louisiana Gov. Kathleen Babineaux Blanco (D) said from Baton Rouge, appearing with U.S. Coast Guard Vice Adm. Thad W. Allen, in charge of the federal Katrina response. "Our efforts to keep a communications network up have paid off."

The differences in the scale of the two storms were plainly visible. Katrina triggered an "ultra-catastrophe," in the words of Homeland Security Secretary Michael Chertoff -- cutting a 90,000-square-mile swath across three states, before triggering a flood that swamped the nation's 35th-largest city and broke down civil order.

In addition to its bigger size, Katrina also struck later in the day than Rita and moved north more slowly, hampering efforts by air crews to get aloft during daylight to grasp its impact.

After Katrina, Lowder said that "basically, everything was shut down for so much longer. This one [Rita] moved out faster; we were able to gather more information quicker."

In last week's run-up to the storm, U.S. officials took advantage of a second chance to test the nation's emergency response system after its near-collapse in New Orleans. Preparations dwarfed those before Katrina.

Bush appeared yesterday morning with Chertoff at the military's U.S. Northern Command headquarters in Colorado, which mobilized thousands of troops and fleets of aircraft and ships.

Two days before landfall, Bush declared Rita an "incident of national significance" -- which triggers the federal government's highest level of response -- and Chertoff named Coast Guard Rear Adm. Larry Hereth as the federal officer in charge. Those steps were taken two days after Katrina hit.

Texas called 10,000 National Guard members and asked for 10,000 active-duty U.S. military troops, while Louisiana has 22,000 guard members in place and asked for 15,000 troops. By comparison, Louisiana readied 5,000 National Guard members before Katrina.

The Pentagon moved 500 active-duty troops into the region yesterday. Blanco asked for 40,000 troops two days after Katrina hit; the White House sent the first 7,000 three days later.

Rear Adm. Joseph F. Kilkenny, commander of Carrier Strike Group Ten, 1,100 sailors and 650 sometimes queasy Marines were aboard the USS Iwo Jima in heavy seas yesterday in the Gulf of Mexico as it steamed toward Sabine Pass, Tex., on the Texas-Louisiana border to help rescue victims of Rita.

Crews started at daybreak yesterday flying 15 helicopters on search missions over Lake Charles and Lafayette, La. Kilkenny said the military is using a grid system designed for fighting wars to carry out its domestic disaster response for the first time. Grids 15 by 15 nautical miles should make searches much more systematic than the chaotic searches after Katrina, Kilkenny said, because all the search parties -- state and local, U.S. Coast Guard, National Guard and active-duty military -- will work from the same grid.

In "Afghanistan and Iraq we used the grid system. In that instance they were called 'kill boxes.' In this instance they're called 'rescue boxes,' " Kilkenny said.

By air and sea, Kilkenny said the Coast Guard was handling rescue from the Texas-Louisiana border westward, while the U.S. Navy was operating east of the border.

In terms of ground operations, Kilkenny said, "This will be a pincer movement. We'll have land forces and FEMA state and local coming from the north down into these areas. And we will survey and see if we need to come in from the sea to render assistance" by sending Marines ashore.

Once it stops 25 nautical miles south of Sabine Pass early today, the amphibious assault ship could also provide medical assistance to people who cannot get help at local hospitals. The ship has 80 doctors and nurses aboard.

There are two other amphibious assault ships, the USS Shreveport and the USS Tortuga, in the Gulf area, as well as the USNS Comfort, a hospital ship, and the supply ship USNS Patuxent. They and the USS Grapple, a rescue and salvage vessel, could join the Iwo Jima as needed. Within about two days, seven or eight Navy mine countermeasure ships are to arrive to help assess damage to offshore oil platforms.

As Rita approached, federal emergency managers positioned twice as many search-and-rescue teams in Texas as they did in Louisiana last month. Officials fueled more that 900 buses for evacuation and rescue, and placed on standby 12 heavy-lift military helicopters, six transport aircraft and dozens of civilian aircraft -- equipment in short supply immediately after Katrina.

FEMA last week stockpiled 45 trailers of water, 45 trailers of ice and 25 trailers of ice in Texas before Rita's arrival, twice as many as last month at Louisiana's Camp Beauregard.

"The big difference is that we have been gearing up our entire system for a month now," Robert B. Stephan, assistant secretary of homeland security for infrastructure protection, said in Washington. "There's no warm-up period -- the car is started and ready to go."

Hendrix reported from Austin. Staff writer Ann Scott Tyson, aboard the USS Iwo Jima, contributed to this report.

A helicopter tries to repair a breached New Orleans levee that was damaged by Katrina and overcome by the effects of Rita.

Loveless Touchet carries his neighbor's child, Kaitlyn Ardin, to a Louisiana Army National Guard vehicle as the rest of her family gets off a boat in Erath, La.Soldiers wait in a hangar in Fort Hood, Tex., for Chinooks to arrive from Midland. The Chinooks were to be deployed for relief efforts.