The image is one of five that Lange took in Nipomo, California, during February or March of 1936. The five are within the Farm Security Administration collection in the Prints and Photos Div of the Library of Congress. LC gives a brief overview of the set.
Here are two more from the set of five:
This photo shows Lange with her enormous 4x5 Graflex.
Here are some more of her photos, all taken in California between 1935 and 1939.