RV users are well aware that they are under public scrutiny. In defense, they insist that the problem-causing riders are "just a few bad apples." "I don't quite get the environmentalists' take on the outdoors," says Ed Klim, president of the American Snowmobile Manufacturers' Association. "It's almost like a religion with them. When they see us on our machines at a trailhead, they say, 'Oh no, we don't want you anywhere near us in the outdoors!' But we say, 'You want to cross-country ski? Fine, we're glad to share the trails.' We snowmobilers don't give a shit who's out there with us. We just want to have fun!"

There are indeed ORV groups that stress lawful behavior, on-trail manners, and environmental good deeds. Montana's Trail Vehicle Rider's Association encourages its more than 300 dirt bikers and ATV-ers to ride their machines at modest speeds and only on legal trails, to quietly pull their vehicles off-trail whenever they meet hikers or horseback riders, and to remove their helmets and goggles so as to look less like space invaders. It also instructs members to wash down their vehicles before riding into the backcountry (to prevent the spread of alien weed seeds into alpine meadows) and to spend several days each summer repairing ORV trail damage. "I'm persuaded that, given the opportunity and direction, riders will do the right thing," says the association's former president Russ Ehnes. Environmentalists tend to regard such intentions and deeds as political nods, too little and too late. Even the most reform-minded ORV clubs regularly petition to have more public land devoted to motorized use, they point out; and only a tiny fraction of the nation's ORV users consent to belong to such clubs in the first place, because it curbs their independence.

Across the country, land managers regret giving off-road vehicles a foothold. "Back in 1974," says Tom Clifford, supervisor of Montana's Helena National Forest, "a Forest Service old-timer, Lee Redding, warned a bunch of us young foresters about these new machines. We were sending out the wrong message, he said, letting them ride wherever they wanted. But none of us took him seriously. We thought we were supposed to accommodate what the public wanted and that we had more than enough land to satisfy everybody. Now I suddenly realize we don't have enough land. If all our visitors were backpackers or canoeists, going quietly along at two or three miles an hour and making a minimal impact on the land, sure, we'd still have enough room for everybody to do his own thing. But a rider on one of today's off-highway vehicles has a far greater radius of travel and sound. We've opened up a Pandora's box, and we're not sure yet how to get it closed."

Closing it, environmentalists feel, is mostly a matter of enforcing existing law. In regulating ORVs, all federal land-managing agencies are bound by two executive orders -- one issued by President Nixon, in 1972, one by President Carter, in 1977. Together, they direct the agencies to monitor the impacts of off-road vehicles upon the land, and to permit or deny ORV use based on these periodic evaluations.

But in a 2000 study of snowmobile and personal watercraft use (ATVs and dirt bikes were not studied), Congress's General Accounting Office discovered that 60 percent of the federal land units it surveyed had not collected any information at all on the impacts of ORVs. Without the required monitoring, the accounting office concluded, the agencies "are not in compliance with [the] Executive Orders" and "have no assurance that they are fulfilling their responsibilities to protect their units' resources and environment from adverse effects." Indeed, only a handful of the state and federal land areas originally traversed by off-road vehicles, either legally or illegally, have since been closed to them.

Few land managers believe that ORVs can be completely removed from public land. Several states, including California, have recently begun to spend a larger portion of their ORV budgets on law enforcement and a smaller portion on trail construction for the vehicles. To control spread of the machines on its 2.1 million acres of state forest land, Pennsylvania now provides roughly $750,000 in annual matching grants to local governments and private entrepreneurs willing to create ATV trails on already-scarred land such as abandoned gravel pits and strip mines.

"We're trying to create a reasonable solution to a tough problem," says Michael DiBerardinis, Pennsylvania's Secretary of Conservation and Natural Resources. "Off-highway vehicle use is growing, but so is our citizens' reluctance to encounter these machines on public land. We're going to subsidize good, challenging trails for them where they'll help local economies, do minimal damage to the environment, and won't interfere with other visitors."

Russ Ehnes, who is also executive director of the National Off-Highway Vehicle Conservation Council, does not like the sound of a plan that limits riders' scenic horizons. "There's no reason we should be shunted off into secondary locations," he says.

Adena Cook, public lands consultant to the Blue Ribbon Coalition, an Idaho lobby group, argues that, especially with an aging U.S. population, ORVs are the only way to give senior citizens access to the wilds they hiked as youngsters. "Now that they're Grandma and Grandpa, what are you going to do with them," she poses, "bring them out to the mountains on a soft-tired ATV, or force them to stay at home?"

Larry Steinbrink briefly ponders that question. "As a grandpa," he says, "it's the vehicles that are keepin' me out of the mountains these days. That's what people should be thinkin' about, instead of worryin' what might happen if I get too old and sick to walk… But if that day comes, and somebody offers to haul me outdoors on one of those damn machines, I'd tell him, 'No thanks. I'd rather be dead.'"