I have ridden numerous trails in the southwest U.S., mostly with our 4WD Club, the New Mexico 4-Wheelers.  So far, we've traveled to parts of Colorado and Utah, and of course, all throughout of wonderful state of New Mexico.  I've "tracked" all of our trail adventures with my Garmin GPS.  The trails are under the links below, by state.  I've included a difficulty rating and the general location of each trail.  Within each trail page, I've included a full-size color map suitable for printing (created using DeLorme's Topo USA software), and a table with the GPS (latitude/longitude) coordinates for each of the waypoints.  Below is the system I use to rate the difficulty of each trail:

For information on other trails, all throughout the U.S., check out http://4wheeldrive.about.com/cs/trailsandmaps/index.htm

Notice: Off-highway travel is by its very nature potentially dangerous and could result in property damage, injury, or even death.  If you drive any of the trails on this web site, you acknowledge these risks and assume full responsibility.  You are the final judge as to whether a trail is safe to drive, whether your vehicle is capable of the journey, and whether your skills are up to the challenge.  The publisher of this web site disclaims any and all liability for property damage, bodily injury, or death that could occur to you or any of your passengers.  On a different note, please be good stewards of our sport--always stay on designated trails . . . and always, always remember to Tread Lightly!