2003. Napa County Conservation, Development Planning. Napa County Viewshed Roads per the Viewshed Protection Ordinance. Napa County (Calif.). County Of Napa.
2012. Patterson, Tom and Kelso, Nathaniel Vaughn. This polyline shapefile represents roads worldwide. The data was derived from a database at 1:1,000,000 scale (but holds up to 1:250,000 scale), co... North American Cartographic Information Society.