Sylvan Pass
Sylvan Pass is a mountain pass
Mountain pass
A mountain pass is a route through a mountain range or over a ridge. If following the lowest possible route, a pass is locally the highest point on that route...

 located in the Absaroka Range
Absaroka Range
The Absaroka Range is a sub-range of the Rocky Mountains in the United States. The range stretches about 150 mi across the Montana-Wyoming border, forming the eastern boundary of Yellowstone National Park and the western side of the Bighorn Basin. The range borders the Beartooth Mountains...

 in Yellowstone National Park
Yellowstone National Park
Yellowstone National Park, established by the U.S. Congress and signed into law by President Ulysses S. Grant on March 1, 1872, is a national park located primarily in the U.S. state of Wyoming, although it also extends into Montana and Idaho...

 in Wyoming
Wyoming is a state in the mountain region of the Western United States. The western two thirds of the state is covered mostly with the mountain ranges and rangelands in the foothills of the Eastern Rocky Mountains, while the eastern third of the state is high elevation prairie known as the High...

. The pass provides access to the park from the east entrance.

The pass was named after nearby Sylvan Lake (derived from medieval Latin sylvānus, from Latin Silvānus, god of the woods, from silva, forest), and was formed by frost action breaking the rocks. The park road through the pass was closed during winter but is now open to visitors throughout winter. The road is maintained to allow access via snowmobile, snow coach
Snow coach
A snow coach is a specialized passenger transport vehicle, designed to operate over snow or ice, similar to alarge, multi-passenger snowcat that is equipped with bus style seating. These vehicles may have multiple sets of very large low pressure tires or they may have tracks...

, and cross-country skiing. In the 2007-08 season it cost the parks service in excess of $200,000 to keep it open and avalanche control measures were put in place.

The Sylvan Pass route is the only way to enter/exit Yellowstone National Park from the East Entrance.

The original road through the pass was designed by Captain Hiram Chittenden of the Army Corps of Engineers.
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