PhilaMercury

Richard Frajola's incredibly rich database of over 11,000 U.S. and foreign 19th Century postal stamp covers. This site, meant as a research resource, allows users to add covers and descriptions from their own personal collections. Includes detailed information and high res scans of each cover, often front and back. There's also a discussion forum, and a variety of special features ranging from the Gold Rush Sampler to the Pony Express Exhibit.