Our distances are not driving distances, but are calculated as a 'straight-line' (or point-to-point) distance from Cortelyou. A straight line distance ignores things like rivers, canyons, lakes, et cetera - it's truly a line drawn from Point A (ie- Cortelyou) to Point B.
Our distance measurements begin at a specific point in Cortelyou. The point that we are using is located at these GPS coordinates - Latitude: 31.4235, Longitude: -88.0083 [Map]. In this case, the coordinates for Cortelyou have been provided by the Geographic Names Information System (GNIS).