Snowmobile use in Yellowstone National Park -- long a bone of contention between aficionados of motorized snowsleds and environmentalists -- has taken an inexplicable plunge, according to a story last week in the Star-Tribune of Casper, Wyo.
The story, widely distributed this week by the Coalition of National Park Service Retirees, says snowmobiles entering Yellowstone have dropped from a peak of 60,000 per season in the 1990s to 10,000 by the winter of 2004-05. The reason, the report points out, is because nearly half the visitors entering Yellowstone do so on park snowcoaches.
The report said that since opening Dec. 20, 1,077 snowmobilers had entered the park while 1,005 visitors rode snowcoaches, a minibus on treads which is quieter and more environmentally friendly.
According to CNPSR, the new snowmobiles remain "much dirtier
than light-duty cars and trucks," and that 250 snowmobiles per day in the park cause more air pollution than 60 times that amount of automobile traffic in the summer. According to a recent report from the National Park Service cited by CNPSR, "Most of the gain in air quality can be attributed to the smaller number of snowmobiles."
EDIT
http://www.boston.com/sports/other_sports/skiing/articles/2007/01/04/park_visitors_enjoy_fresh_approach/