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.
Mexico circa 1891. "Ferrocarill Central Mexicano. Canal of Nochistongo," a drainage excavated in the 17th and 18th centuries to keep Mexico City from flooding. Note the giant camera and tripod employed by William Henry Jackson in the making of his heroically proportioned photographs, the largest of which were recorded on a medium the archivists call "mammoth plates" -- glass negatives that measured 18 by 22 inches. (This particular image was made on an 8x10 inch glass plate -- what modern photographers would consider "large format," but still only a fifth the size of an 18x22.) Detroit Publishing Co. glass negative. View full size.