Here are some excellent sources for obtaining digital images. Always be sure to check for copyright and any other use restrictions before using any image.
A picture is very often truly worth a thousand words as is the case with this iconic photograph of a migrant mother taken in California in 1936 by Dorothea Lange. It has come to epitomize the Great Depression. (Source: NARA)
This film, shot by the Miles brothers, was made on April 14, 1906, only four days before the San Francisco earthquake. It was taken from the front window of a moving cable car.