All but three of the 1,400 animals in New Orleans’s famous Audubon Zoo survived Hurricane Katrina, according to zoo officials, who said they had been planning for such a catastrophe for years.

The results were grimmer at several hospitals and nursing homes. Although doctors, nurses, and rescue workers labored heroically for days, an unknown number of frail patients died in flooded, darkened buildings with no air-conditioning, no electricity to support ventilators and other life-saving equipment, and little nourishment. Their bodies are still floating in hospital morgues and corridors.

Emergency crews arrived at a nursing home in Chalmette, La., just south of the city, to find 31 residents dead in the floodwaters. At another nursing home in St. Bernard Parish, 30 more died.

This carnage could have been prevented with sounder decisions by local officials ahead of time. In a crisis – natural or man-made – the first place you think to go is a hospital. That’s why hospitals have to be able to continue caring for their patients and take in many more. Here’s what other cities and states need to learn, so their own hospitals won’t become death chambers.

New Orleans is a city below sea level, where flooding is expected. Yet virtually all hospital emergency rooms and generators were on the first floor and quickly disabled by floodwaters. In California, the threat is different – earthquakes. In 1994, an earthquake disabled 23 hospitals in the Los Angeles area. Immediately after, the California Legislature enacted a law requiring hospitals to strengthen their buildings against seismic disasters by 2008, but the California Hospital Association is pressing to extend the deadline. Perhaps they know when the next earthquake is coming.

After Katrina, every hospital bed within 100 miles of New Orleans was filled, and there was no blueprint showing where patients could be accommodated as the numbers continued to swell. On the third, fourth, and fifth days of the disaster, when patients were being trucked and airlifted out of the city, administrators in some public hospitals had no idea where the patients – including day-old newborns – were being taken and how they would be located later.

How ready are other cities for a surge in patients? Since September 11, 2001, federal officials have urged localities to prepare for a huge increase in hospital demand in the event of a terrorist attack. Local officials have ignored the warnings. Washington, D.C., received $145 million in federal funding to prepare its hospitals, including increasing surge capacity. Nearly all the funds are still unused.

Last April, Milwaukee conducted a mock disaster drill, which presumed that 100 people were injured and needed hospital care. Last June, New Orleans held a similar drill, also premised on having to care for 100 injured people. How realistic is 100 people? Ridiculous. The federal government has warned that a typical terrorist act – such as blowing up a chlorine truck – would result in 100,000 injured. “Hospital preparedness is an exercise in fantasy,” a former federal health and human services preparedness chief, Jerome Hauer, said. “Most people think that having 100 beds is surge capacity. But most cities, if they were to have 10,000-15,000 patients, would be brought to their knees.”

Concerned with that prospect, Governor Rell of Connecticut proposed purchasing a modular, M*A*S*H-style hospital, about the size of a football field, which could be erected and put into operation in 12 hours anywhere in the state. But last spring, the Connecticut Legislature deemed it unnecessary. In view of New Orleans’s fate, perhaps the Legislature will reconsider.

One of the many tragedies in New Orleans occurred when a man rushed his mother to Charity Hospital because she needed a ventilator to breathe. The hospital, lacking electricity, had to turn them away, and he watched her die. To avert such calamities, civilian officials can learn from the U.S. Air Force, which has equipped its battlefield medical teams in Iraq with ventilators and other equipment in backpacks and trained them to deliver critical care outside of a bricks-and-mortar hospital. The result? The death rate from combat wounds has dropped to the lowest in modern history. Perhaps police, fire, and other medical rescue teams should be equipped with similar packs to deliver more critical care on-site rather than triaging and transporting patients.

New Orleans is a costly reminder that local officials and health experts elsewhere must prepare hospitals for future disasters. In a time of crisis, the zoo should not be the safest place to be.

Ms. McCaughey is a former lieutenant governor of New York State and adjunct senior fellow at the Hudson Institute.