Found this, and thought it's quite interesting. Just download to your current gps unit.Hmm
ATVGPS National - atvgps.net
ATVGPS National puts detailed ATV trail maps of Alabama, Arizona, Arkansas, California, Colorado, Delaware, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, Oklahoma, Oregon, Pennsylvania, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin and Wyoming onto your Garmin GPS. (Click on a state name to view its ATVGPS trails.)
Please note that this set does NOT currently include the following states: AK CT HI ND NE OH RI.
Whether you've got a handlebar-mounted zūmo, a rugged Garmin eTrex, or a popular Garmin nüvi, ATVGPS will turn it into a off-road ATV navigator.
Everyone knows where the roads are and many people use topographic maps to see elevation information. But what about the ATV trails? Trail intersections? Trailhead parking? Our partner, US TrailMaps, has mapped over 10,000 miles of ATV trails, together with the supporting ATV-specific points-of-interest.
It takes less than 30 seconds to put these maps onto your compatible GPS: simply slide the memory card in, check the maps are visible, and off you go!
ATVGPS puts together US TrailMaps' off-road and recreational mapping with Mountain Dynamics' proven experience in delivering and supporting Garmin-compatible maps.
Please use common sense when navigating using ATVGPS, stay on the trails, and be sensitive to the rights of private property owners and land managers who allow access to their land. The presence of a trail on a ATVGPS map does not guarantee that you have access to the trail. Obey posted restrictions and applicable laws.