If you're concerned with the negative stereotyping in the press that the sport of 4-wheeling has garnered due to a few irresponsible riders, there is a group in Maryland that shares your concern. The United Riders ATV Club of Maryland decided they would try to change the perception that 4-wheeler riders are irresponsible trespassers who really don't care about the impact they have on the environment, as long as they are free to ride.
The United Riders ATV Club clearly states that their mission is to ride safely, have fun, and keep peace with those that allow us to ride on their properties'. To this extent, the club obtains written permission for the lands that they ride on, and challenges other 4-wheeler enthusiast to do the same.
This 4-wheeler club rides most weekends during the regular season. The group usually meets at a predetermined location, and the number of riders who show up determines which 4-wheeler trails they'll ride that day. United Riders always keep safety foremost in mind, so big groups will only ride on 4-wheeler trails large enough to accommodate them. But be prepared for a real ride because club members say they usually cover 45 miles on an average ride.
The club maintains a photo album on their website, so you can get a feel for how large the groups usually are and the types of terrains they like to ride. Also, don't think this group is a "boys club" only, ladies are more than welcome to don their favorite 4-wheeling gear and hit the trails!