Our distances are not driving distances, but are calculated as a 'straight-line' (or point-to-point) distance that stretches from Jefferson Park. A straight line distance ignores obstructions like rivers, canyons, lakes, et cetera - it's truly a line from Point A (ie- Jefferson Park) to Point B.
Our distance measurements begin at a specific point in Jefferson Park. The point that we are using is located at these GPS coordinates - Latitude: 33.5418, Longitude: -86.6444 [Map]. In this case, the coordinates for Jefferson Park have been provided by the Geographic Names Information System (GNIS).