Our distances are not driving distances, but are calculated as a 'straight-line' (or point-to-point) distance starting from Hart. A straight line distance ignores obstructions like rivers, canyons, lakes, et cetera - it's truly a line from Point A (ie- Hart) to Point B.
Our distance measurements begin at a specific point in Hart. The point that we are using is located at these GPS coordinates - Latitude: 35.2889, Longitude: -115.1033 [Map]. In this case, the coordinates for Hart have been provided by the Geographic Names Information System (GNIS).