Jack Ohman's cartoon reflects the perennial battle over how 'pristine' America's great national parks should be, i.e. how like they were before the European settlement of North America. There has to be some access for visitors, but how much and for how many people and by what means remain controversial issues.
In the left frame of the cartoon, we see two people hiking through the snows of Yellowstone National Park, in which the most famous of the many geysers is 'Old Faithful'. The hikers think it lies just over the hill, where the column of vapor is rising. The scene is silent, the snow undisturbed except for the tracks left by the hikers. Hiking represents a very benign sort of access to nature: little preparation of the park is required; little in the environment is disturbed.
Suddenly (in the right frame) the silence is broken by the roar of a vehicle speeding over the hill. It's a snowmobile, a loud, polluting conveyance that zips quickly over snow and ice. True, today's snowmobiles aren't so loud or polluting as they used to be, but they're still pretty upsetting to anyone looking for communion with nature. In any case, many snowmobilers like the noise, just as many people who drive motorboats or fast cars do. Snowmobilers think of national parks as public playgrounds, and what's a playground without noise?
During the Clinton years, the government inaugurated a plan to reduce the human impact on the parks, especially the much-visited ones like Yellowstone in Wyoming and Yosemite in California. A ban on the recreational use of snowmobiles was being phased in until the Bush administration canceled it. Nature lovers took the government to court, insisting that the ban was essential in order to protect the environment inside the parks, as mandated by federal law. In December the courts sided with the plaintiffs, reinstituting the plan for a park without recreational snowmobiles. The Bush administration plans an appeal.