Snowmobiling is legal in Yellowstone, but there are several restrictions. Until December 2014, snowmobiles are only allowed on the roads. From December 2014, a very limited number of snowmobile groups will be allowed in the park each day during the winter.
As of December 2014, snowmobile groups are limited to 51 groups per day, with no more than 10 snowmobiles per group. This regulation is intended to limit air and noise pollution in the park. The National Park Service lists several local snowmobile companies that are approved for guided tours in the park.
From 2015, snowmobiles used in the park will need to pass noise and air pollution standards to further curtail their impact on the park's resources.