This is a Message Board Post that is gatewayed to this mailing list. Classification: Query Message Board URL: http://boards.ancestry.com/mbexec/msg/an/AFB.2ACI/4731.1.1.1.1.2.1 Message Board Post: Well - the fine print says that a viewer is not necessary to view this map online, so I guess that's not it. I copied the info about downloading the map. Download Digital Images No special viewers are required to view maps in the American Memory collections. American Memory maps are presented, via your browser, as .gif (Graphics Interchange Format) files. A compression technology, called MrSID (Multi-Resolution Seamless Image Database) developed by LizardTech, allows you to zoom in or out on an area of the map that you wish to inspect. Maps are stored in .sid format. The MrSID .sid files of American Memory maps are available to download to your computer. The download option is available at the bottom of the "Zoom View" page for each map. The average size of files in the .sid format is 5 megabytes.