America from the Great Depression to World War II - Photographs from the FSA-OWI, 1935-1945.  "The images in the Farm Security Administration-Office of War Information Collection are among the most famous documentary photographs ever produced. Created by a group of U.S. government photographers, the images show Americans in every part of the nation."

American Photography: A Century of Images - Web site for a PBS feature presentation of the same name.

Reflections in Black: a History of Black Photographers - A Smithsonian exhibition of black photographers from 1840 to the present which presents a pictorial history of black Americans as photography was evolving.

USDA On Line Photography Center - "The Center's mission is to acquire and make available useful photography depicting general agriculture, health, economics, resource conservation, forestry, and other programs administered by the agencies of the United States Department of Agriculture."