Map Your Run (and not with a compass)
There are several ways to plan a route of a certain distance for running or walking. You can drive it in your car, ride it on your bike, use your GSP the first time you run it, but if you want to plan in advance without ever leaving home, we suggest one of the following sites. They are easy to use. Most allow you to save your routes and even share them with other runners & walkers.
Route Mapping Sites
MapMyRun's Route Planner
(MapMyRun.com is a site where you can easily plot maps of where you've route, find various routes / running trails in a certain area, keep track of your routes including distances, and even calculate how many calories you've burned on one route verse another! (that is directly from the website)
G-Map Pedometer (map a route anywhere in the US)
USATF's GPS maps (measure courses by clicking on a map)