Most of the photos on this site were extracted from reference images (high-resolution tiffs, 20 to 200 megabytes in size) from the Library of Congress research archive. (To query the database click here.) Many were digitized by LOC contractors using a Sinar studio back. They are adjusted by your webmaster for contrast and color in Photoshop before being downsized and turned into the jpegs you see here.
Chicago, December 1942. "Hump master in a Chicago & North Western railroad yard operating a signal switch system which extends the length of the hump track. He is thus able to control movements of locomotives pushing the train over the hump from his post at the hump office." 4x5 Kodachrome transparency by Jack Delano for the Office of War Information. View full size.