OpenStreetMap Project Imports US Government Maps

“OpenStreetMap (OSM) is a collaborative project in the process
of building a free, Web-accessible, user-editable map of the world.
So far, most of its map data has come through user-contributed GPS
traces, but OSM has recently undertaken the bulk import of
government-collected data covering the entire United States. The
massive import will jump-start OSM’s US map coverage, but its sheer
size poses an interesting challenge to the project’s resources.

“The traditional method of importing data to OSM is outlined on
the project’s wiki: Individual users collect GPS traces, convert
the tracks to OSM form, label any objects, then upload the result
to the OSM database. Map images themselves are rendered separately,
as needed…”