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.