Readex, a publisher of online historical collections, has announced that it will provide customers with access to the more than 50,000 maps within its digital edition of the U.S. Congressional Serial Set, 1817-1980. Readex is adding authoritative cartographic records monthly and will continue until every Serial Set map carries a record. Featuring thousands of maps designed to enable users to visualize the history and territorial growth of the United States, the cartographic information in the U.S. Congressional Serial Set will be available to search and browse. Renowned works include the American Civil War Atlas, maps delineating the boundary between the United States and Mexico, and John C. Fremont’s map, which was carried westward by scores of early settlers. Also included are many maps addressing subjects such as the spread of cholera throughout Persia, the theatre of war in the Crimea, and the river system and dams of the Indian Subcontinent. In addition to adding map records to the Serial Set, Readex has incorporated a new image viewer--the same version found in America’s Historical Newspapers--that allows users to zoom in and print all or part of the high-resolution maps and color illustrations.