The USGS library, my oh my how cool is this?

The USGS Photographic Collection is a national treasure held in trust by the Central Region USGS Library. This archival collection of photographs dating from the 1870′s includes works of such pioneer photographers as W.H. Jackson, J.K. Hillers, and T. Moran. Images from the Photo Collection are being scanned and added to the Library’s historic photo website. 38,000 photos are available and may be searched by caption keywords or browsed by photographer or topic. Scanned images of these photos are in the public domain and can be viewed and downloaded at a variety of resolutions
free of charge.  AWESOME!