As the fifth anniversary of Hurricane Katrina approaches, the American Red Cross has published a report detailing its work on the Gulf Coast.

The combination of Hurricanes Katrina, Rita, and Wilma redefined what a big disaster looks like in the United States, says the charity.

Before Katrina, the 2004 hurricane season stood as the largest domestic disaster in American Red Cross history. Responding to the four hurricanes that battered Florida that year, the organization provided assistance to 73,779 families and individuals. After the 2005 hurricanes, that figure was 1,407,075—more than 19 times as many people.

The price tag for relief efforts after Katrina, Rita, and Wilma was more than 17 times greater than the cost of responding to the 2004 storms—almost $2.2-billion compared to $127.8-million.

The 2005 storm season changed the way the Red Cross prepares for large emergencies, says Joe Becker, senior vice president for disaster services at the Red Cross.

“We learned where our systems weren’t big enough,” he says. But by the 2006 hurricane season, the organization had stockpiled enough supplies to provide shelter for twice the number of people it had housed after Hurricane Katrina, he says.

Listen to Mr. Becker talk about the other important lesson the Red Cross took away from the 2005 storm season: the need to build stronger ties to local nonprofit and faith groups.