Downtown Three Forks’s [1] historical Headwaters Heritage Museum (202 S. Main St., 406/285-4778, Mon.–Sat. 9 a.m.–5 p.m. daily June–Sept.; free) has a good collection of photographs and an archaeological display among the exhibits. But perhaps most memorable is the mount of a 29.5-pound brown trout—the largest ever caught in the state.
Links:
[1] http://www.moon.com/destinations/montana/the-missouri-headwaters-and-south-central-montana/three-forks-and-the-madison-river/three-forks