Politicians and emergency officials all over the country have pledged to re-evaluate disaster plans and resources — after Katrina proved how easily law and order can be lost, how fragile and flawed the telephone infrastructure can be, how important it is to have food and water readily available, how the poor and disabled are especially vulnerable in a disaster.

Another paramount lesson for many: The federal government cannot be counted on for immediate help. Localities and even individuals must have their own emergency plans.

"We can't expect meaningful federal support to be on the ground providing provisions in an organized manner until probably the seventh day," said Eric Holdeman, with the King County, Wash., Office of Emergency Management in Seattle. "Our emergency response system is geared toward everyday emergencies, not disasters. . . . People need to be able to help themselves."

If it happened . . .

Others agreed an event as large as Katrina cannot be managed by any city or state alone. Tennessee's capacity to house evacuees was spent completely by Katrina, as it absorbed about 20,000 people. What if, like New Orleanians, Memphis' 650,000 residents suddenly needed somewhere else to go?

Another quake of the magnitude of the 1812 temblor hitting Memphis could supplant Katrina as the country's worst natural disaster. Most of downtown Memphis, made of brick and concrete, would fall. Bridges and highways would be shattered. Gas lines would rupture. And the Mississippi River, if already near flood stage, could put large parts of Arkansas underwater.

None of these predictions are new. But they're real now.

"I don't think we've ever talked about pre-positioning food caches before," said Kurt Pickering, spokesman for the Federal Emergency Management Agency's office in Tennessee. "I thought we'd never be able to fund satellite telephones. . . . I don't want to tell the legislature how to spend the state's money, but I'm thinking now it might be doable because of Katrina."

Two states upriver, St. Louis suffered through a devastating flood only 12 years ago. The day Katrina hit the Gulf Coast, local emergency managers started reviewing flood plans in the area, which is also prone to tornadoes and is within the New Madrid seismic zone.

"It says it could happen here," said St. Louis emergency director Gary Christmann.

Lessons learned

Los Angeles, which has been through earthquakes, wildfires and riots, is as well prepared as any city for a large-scale disaster. All kinds of heavy equipment and a satellite communications system are available to Los Angeles County. Thousands of National Guard and California Highway Patrol officers are based in Los Angeles.

But Katrina made even officials there think again. They now recommend, for instance, that residents keep five to seven days of food and water on hand instead of the three days' worth that were previously recommended.