Southwest of Madison in the Beaverhead-Deerlodge National Forest, there is an extensive snowmobile trail system.
Red Rock Pass/Elk Lake (#2) - A 13 miles one-way route from Red Rock Pass to Elk Lake. There are some narrow, winding sections on this more difficult route.
Antelope Basin - Horn Creek Cutoff (#2A) - A 6 mile connecting trail from Antelope Basin to Route 3. The moderate route rolls through open country.
Antelope Basin (#2B) - A 7 mile route through Antelope Basin to Route 2 at Jct A. This is an easy route, but keep an eye out for fence posts in the snow.
Spring Branch (#2C) - A 8 mile route connecting #2 and #2B. Moderately difficult.
Horn Creek (#3) - a 10 mile route connecting Hwy 287 to Hwy 87. This easy route provides access to Cliff and Wade Lakes.
Freeseout Loop (#5) - a diffucult 13 mile around Flatiron Mountain.
West Fork Cutoff (#5A) - a 6 mile cutoff trail connecting Route 5 to Route 7 at Jct. J. This is a difficult route and it can be easy to get stuck.
Black Butte Loop (#7) - 50 mile loop beginning and ending at the Lyon's Bridge Trailhead.