Database of thousands of public domain stock photographs that may be used for both personal and commercial users.   Each photo has a license that clearly states allowable uses of image. According to the site, "unless something is clearly marked as being something other than public domain, you can assume it is free to use".  If you wish to use the image for commercial uses, be aware that model releases were not obtained.  Can search for photos by category or keyword.

Over 2000 photographs that are advertised on the site as "100% free for use" including for commercial redistribution and alteration.  Photographs are arranged by categories such as arts, people, objects, technology, transportation, nature, sports, etc.

Thousands of on-line, copyright free photographs of Franklin and Eleanor Roosevelt, the Great Depression and the New Deal, and World War II. Find images of WPA (Works Progress Administration) projects, World War II training camp maneuvers and shipbuilding and hundreds of photos of Franklin Roosevelt.  Photographs can be easily downloaded or print copies can be ordered for a fee. 

A portal to U.S. Government images and photos. Includes links to image rich government sites such as the Library of Congress, branches of the military, the U.S. Mint and the National Park Service. A wide range of images are available, from historical baseball featured in the Spalding Base Ball Guides to satellite images taken by the Landsat-7. "Most of these images and graphics are available for use in the public domain, and they may be used and reproduced without permission or fee. However, some images may be protected by license."