In 2013, the National Park Service (“NPS”) promulgated a new rule to regulate the use of snowmobiles and snowcoaches in Yellowstone National Park during the winter months. The innovation and development of such “oversnow” vehicles increased park visitors’ access to Yellowstone’s majestic wonders throughout winter. Unfortunately, because such vehicles emitted noise and air pollution and created safety hazards, their unfettered use throughout the winter season posed an ever-increasing threat to the natural integrity of Yellowstone and to visitors. To mitigate the negative effects of oversnow vehicles on Yellowstone, the NPS began restricting their use by placing fixed limitations on the number of oversnow vehicles permitted to operate within the park. These early regulations were met with various legal challenges, advanced by oversnow vehicle proponents and opponents alike. In response, the NPS created a new framework for limiting use in the 2013 rule structured around the “transportation event,” as opposed to setting fixed limitations. This Note engages in an analysis of this novel framework and argues that utilization of the transportation event scheme strikes the appropriate balance between conservation interests and allowing access to the park’s resources. Nevertheless, the rule remains vulnerable to potential legal attack.