San Francisco circa 1921. "Gardner car at Spreckels Mansion." Photographed by and with Christopher Helin himself. 5x7 glass negative. View full size.

July 1939. "Housing conditions in Ambridge, Pennsylvania. Home of the American Bridge Company." Medium format negative by Arthur Rothstein. View full size.

July 1938. "Boys in the town in front of Greek coffee shop. Ambridge, Pennsyl­vania." Medium format negative by Arthur Rothstein. View full size.

From around 1950 comes this News Archive snap of the Packard Parts counter, possibly in Columbus, Georgia. (When in doubt, "Ask the Man Who Owns One.") 4x5 inch acetate negative. View full size.

Florida circa 1897. "Palm walk on Lake Worth, Palm Beach." 8x10 inch dry plate glass negative by William Henry Jackson. View full size.

February 1941. "Migratory laborers and vegetable pickers playing a game of 'skin' in back of juke joint and bar in the Belle Glade area of south central Florida." Medium format acetate negative by Marion Post Wolcott. View full size.

        One of William Henry Jackson's "mammoth plate" exposures, made using 18x22 inch glass negatives, a massive view camera, assorted assistants, pack animals and a mobile darkroom that he hauled around by rail with chartered locomotives. This image comes from a number of 8x10 copy negatives exposed in the 1890s from the original 18x22 mammoth plates, which evidently are too big or fragile to scan.

1891. "Mexican Central Railway -- bridge over the Santa Rosa River." 8x10 glass plate made from an 18x22 negative by William Henry Jackson. View full size.

February 1939. "Shack of war veteran with view along Nueces Bay. Corpus Christi, Texas." Medium format acetate negative by Russell Lee. View full size.

Circa 1899. "Fox River at Aurora, Illinois. Scene on the Chicago & North Western Railway." 8x10 inch glass negative, Detroit Photographic Co. View full size.

Elmhurst, Illinois, circa 1899. "Chicago & North Western Railway station." 8x10 inch dry plate glass negative, Detroit Photographic Company. View full size.

Detroit, Michigan, circa 1910. "East Grand Boulevard." 8x10 inch dry plate glass negative, Detroit Publishing Company. View full size.

February 1939. "In a carrot pullers' camp, Imperial Valley, California, near Holtville. Women from Broken Bow, Oklahoma." Medium format negative by Dorothea Lange for the Farm Security Administration. View full size.

December 7, 1932. "International Music Hall, Radio City, Rockefeller Center, New York. House with curtain down, from main orchestra." Large-format acetate negative by Gottscho-Schleisner. View full size.

Detroit circa 1910. "Bath house at Belle Isle." 8x10 inch dry plate glass negative, Detroit Publishing Company. View full size.

June 1939. West Carlin, Nevada. "Brakeman on the Union Pacific Challenger." Photo by Dorothea Lange for the Farm Security Administration. View full size.