Lange's best-known picture is titled "Migrant Mother." The woman in the photo is Florence Owens Thompson. The original photo featured Florence's thumb and index finger on the tent pole, but the image was later retouched to hide Florence's thumb. Her index finger was left untouched (lower right in photo).
In 1960, Lange spoke about her experience taking the photograph:
I saw and approached the hungry and desperate mother, as if drawn by a magnet. I do not remember how I explained my presence or my camera to her, but I do remember she asked me no questions. I made five exposures, working closer and closer from the same direction. I did not ask her name or her history. She told me her age, that she was thirty-two. She said that they had been living on frozen vegetables from the surrounding fields, and birds that the children killed. She had just sold the tires from her car to buy food. There she sat in that lean-to tent with her children huddled around her, and seemed to know that my pictures might help her, and so she helped me. There was a sort of equality about it.
According to Thompson's son, Lange got some details of this story wrong, but the impact of the picture was based on the image showing the strength and need of migrant workers.
Florence Owens Thompson
In March 1936, after picking beets in the Imperial Valley, Thompson and her family were traveling on US Highway 101 towards Watsonville in hopes of finding more work. On the road, the car timing chain snapped and they coasted to a stop just inside a pea-picker's camp on Nipomo Mesa. As Jim Hill and two of Thompson's sons left to town to repair the radiator, which had also been damaged, Thompson and some of the children set up a temporary camp. As Thompson waited, Dorothea Lange, working for the Resettlement Administration, drove up and started taking photos of Florence and her family. Over 10 minutes she took 6 images.
Thompson ... claimed that Lange promised the photos would never be published, but Lange sent them to the San Francisco News as well as to the Resettlement Administration in Washington, D.C. The News ran the pictures almost immediately, with an assertion that 2,500 to 3,500 migrant workers were starving in Nipomo. Within days, the pea-picker camp received 20,000 pounds of food from the federal government. However, Thompson and her family had moved on by the time the food arrived and were working near Watsonville.
While Thompson's identity was not known for over forty years after the photos were taken, the images became famous. The sixth image especially, which later became known as Migrant Mother, "has achieved near mythical status, symbolizing, if not defining, an entire era in [United States] history." Roy Stryker called Migrant Mother the "ultimate" photo of the Depression Era. "[Lange] never surpassed it. To me, it was the picture … The others were marvelous, but that was special ... . She is immortal." As a whole, the photographs taken for the Resettlement Administration "have been widely heralded as the epitome of documentary photography." Edward Steichen described them as "the most remarkable human documents ever rendered in pictures." Later, however, the photographers came under sharp criticism for presenting the conditions of their subjects as harsher than they actually were.
It was only in the late 1970s that Thompson's identity was discovered. In 1978, acting on a tip, Modesto Bee reporter Emmett Corrigan located Thompson at her mobile home in Space 24 of the Modesto Mobile Village and recognized her from the 40-year-old photograph. A letter Thompson wrote was published in The Modesto Bee and the Associated Press sent a story around entitled "Woman Fighting Mad Over Famous Depression Photo." Florence was quoted as saying "I wish she [Lange] hadn't taken my picture. I can't get a penny out of it. She didn't ask my name. She said she wouldn't sell the pictures. She said she'd send me a copy. She never did."
Lange was funded by the federal government when she took the picture, so the image was in the public domain and Lange never directly received any royalties. However, the picture and the attention it received gave a big boost to her career.