Google the term "migrant mother" and look at the pictures.
You will know instantly the work of the depression-era photographer Dorothea Lange. Lange died in 1965, but left behind some of the most unforgettable images in photographic history, especially her images of Americans down on their luck.
Lange's goddaughter Elizabeth Partridge places her writing aside Lange's work in the book Dorothea Lange: Grab a Hunk of Lightning.