The hardest hit area in the Dust Bowl was Boise City, Okla., part of the panhandle known as "No Man's Land." Here, a huge dust cloud approaches on April 15, 1935, in Boise City. "The Dust Bowl," a documentary by Ken Burns, airs tonight and Monday night on PBS.

Photographer Dorothea Lange, of the New Deal-era Farm Security Administration, came across Florence Thompson and her children in a pea pickers' camp in Nipomo, Calif., in 1936. During the Great Depression, California's population grew by more than 20 percent, an increase of 1.3 million people.