On August 19, 1895, Dorothea Lange was born in Hoboken, New Jersey. She had polio at age seven, which left her right leg permanently weakened. She later said that polio taught her something she would use for the rest of her career: "It gave me an understanding of people who are disadvantaged, discriminated against."

In 1935, Lange was working for the Farm Security Administration, photographing the effects of the Dust Bowl and the Great Depression on displaced agricultural workers. In March 1936, near Nipomo, California, she stopped at a camp for migrant pea pickers that had been stranded by crop failure. She approached a woman in a lean-to shelter, asked to photograph her, and made six exposures. The woman's name was Florence Owens Thompson.

The photograph Lange selected — Thompson staring directly into the camera, three children pressed against her — was distributed to news organizations and published across the country. Within days, the federal government had sent 20,000 pounds of food to the Nipomo camp.

The photograph is called Migrant Mother. Florence Owens Thompson was Cherokee. She is not identified in the photograph's caption. She told an interviewer in 1978 that she wished Lange had never taken it. "I didn't get anything out of it. She got famous from it."

Lange published it; the FSA owned the negative. Thompson received no compensation and had no control over the image's subsequent distribution. The photograph that mobilized food aid for her camp made Lange's career and gave Thompson no ongoing benefit.

In 1942, the War Relocation Authority commissioned Lange to photograph the Japanese American internment. She was told to document it as orderly and dignified. She photographed what she saw, which was neither. The Army confiscated her photographs. They were classified and not released until 2006.

She died in 1965 in San Francisco, four days before the opening of her retrospective at the Museum of Modern Art.