Roadnav is an in-car navigation system capable of running on a variety of operating systems, including Linux, Windows, and Mac OS X. Roadnav can obtain a car´s present location from a GPS unit, plot street maps of the area, and provide verbal turn by turn directions to any location in the USA. Roadnav uses the free TIGER/Line files from the US Census Bureau to build the maps, along with the GNIS state and topical gazetteer data from the USGS to identify locations.