Since 1977, the agency has lifted or weakened motorized restrictions on 33 trails within the area. Solitude and beauty are in shorter supply. I'd say it's more like an urban experience. In Yellowstone National Park, snowmobile use has exploded to 70,000 trips each winter. One snowmobile emits as much hydrocarbon and nitrous oxide pollution as 1,000 cars.
Bad air is just one of the problems.
This traffic also shatters Yellowstone's winter solitude, replacing the whisper of the wind with the whine of engines. Wildlife such as the grizzly and buffalo are icons of Yellowstone and a West that has disappeared, and they continue to face serious threats. Nearly 2,000 buffalo have been slaughtered over the past several years. Seeking winter forage, these animals usually head north and west out of the park. Once they reach other public lands in Montana, they are frequently shot because of an undocumented fear that they will infect local cattle with brucellosis.