From 1935-1944, the Farm Security Administration — Office of War Information undertook the largest photography project ever sponsored by the federal government.
Photogrammar has a map-based photo gallery of FSA-OWI photos for the decade ending just before World War II ended.
Of interest to me (and maybe very few others) is the fact that Tarrant county in Texas (Fort Worth being the main city there) has over twice as many pictures as Dallas.
Bootstrap users will instantly notice that Photogrammar uses Bootstrap. The map is created with CartoDB.