Using maps as sources requires time and effort on the part of the researcher. The staff of the Geography and Map Division provides skilled reference service that is facilitated by catalogs, bibliographies, inventories, and other finding aids. In addition, large portions of some of the most heavily used historical collections are now available online on the Library's American Memory Web site.

Map collections that are part of American Memory can be located either from the Geography and Map Division's home page or by going to <http://memory.loc.gov/ammem/gmdhtml/gmdhome.html>. The collections are listed under a variety of headings:

• Cities and Towns includes the Panoramic Map Collection, dated 1847-1929
• Military Battles and Campaigns encompasses Civil War Maps, 1861-65 and maps from the era of the American Revolution, 1750-89
• American Colonization Society/Liberia Maps, 1830-70 can be found under the heading Cultural Landscapes
• Railroad Maps, 1828-1900 are filed under Transportation and Communication
• A variety of maps including several atlases dated 1544-2003 are filed under General Maps.
• A multimedia presentation called African-American Odyssey includes maps and can be accessed through the “Using the Collection Finder” part of American Memory under Original Format: Maps.

Scanned map images make use of special features such as location key maps, indexing systems, and “zoom” capabilities. The compression technology does not eliminate any of the pixels of the original, making it possible for users to enlarge portions of the maps in order to see detail that is invisible to the naked eye on the original item. The navigator window outlines the portion of the map that is included in the enlarged image.