Redtrails: Trails Co-Op
Retrails Trails Co-op is a compendium of over 35,000 American trails ranging from National Parks and Forests hikes to local mountain bike trails.
The individual pages for each of the trails includes a Google Map showing the route of the trail. Alongside the map are the trail's details, such as its length and elevation profile. If you zoom the map out you can also view trails that are nearby.
If you select the 'viewer' option you can view all the trails on a Google Earth browser plug-in map. Here the location of the trails is shown with map markers which indicate if these are hiking, biking or climbing trails.