The Madison, Jefferson, and Gallatin rivers come together to form the mighty Missouri River within Missouri Headwaters State Park, a National Historic Landmark. At 2,540 mi, the Missouri is the country's longest river. Lewis and Clark named the three forks after Secretary of the Treasury Albert Gallatin, Secretary of State James Madison, and President Thomas Jefferson. The park has historical exhibits, interpretive signs, picnic sites, hiking trails, and camping.
Trident Rd., 3 mi northeast of Three Forks on I–90, exit at Three Forks off-ramp, then go east on 205 and 3 mi north on 286, Three Forks, Montana, 59752, United States