Our distances are not driving distances, but are calculated as a 'point-to-point' distance from Topaz. A straight line distance ignores things like rivers, canyons, lakes, et cetera - it's truly a line drawn from Point A (ie- Topaz) to Point B.
Our distance measurements begin at a specific point in Topaz. The point that we are using is located at these GPS coordinates - Latitude: 35.0365, Longitude: -90.3593 [Map]. In this case, the coordinates for Topaz have been provided by the Geographic Names Information System (GNIS).