Well before Lewis and Clark camped at the site of Missouri Headwaters State Park (four miles northeast of Three Forks  on Road 286, 406/994-4042, www.fwp.state.mt.us/parks , daylight hours, year-round, camping from May 1–Sept. 30, free for Montana residents, $5 day-use fee for nonresidents), this area where the Madison , Jefferson, and Gallatin Rivers  join up to form the Missouri was well traveled.
It was a disputed hunting area and the site of frequent battles between the Crow and the Blackfeet. The mountain and river bands of the Crow had regular rendezvous at the headwaters, where they’d hunt, fish, and later, trade with whites.
When the Corps of Discovery reached the Missouri headwaters on July 27, 1805, Lewis and Clark concluded that none of the three rivers was sufficiently larger than any other to warrant calling it the Missouri and calling the other two feeder streams. They solved this dilemma by declaring them “three noble streams” and took the opportunity to name them after the President (Jefferson), the Secretary of State (Madison), and the Secretary of the Treasury (Gallatin).
Actually, river-naming was not foremost in Lewis’s and Clark’s minds—they were far more preoccupied with meeting the Shoshone, from whom they hoped to obtain horses.
Try to visit the headwaters early or late in the day, when the light comes in low and opens you up to some special magic held by the rivers and bluffs. Good information stations discuss local flora and fauna as well as Corps of Discovery history.
The headwaters site includes an old hotel and log cabin from Gallatin City, built in 1864 with the somewhat deluded thought that steamboats would be able to navigate to this point. (The city did not thrive.)
A small cave is painted with several faded and damaged Native American pictographs; follow the trail south from the main interpretive center to see it.
If bird-watching appeals to you more than steeping yourself in Lewis and Clark lore, there are herons, ospreys, Canada geese, and songbirds along the headwaters trail. Climb Lewis Rock or Fort Rock to scan the cliffs for golden eagles.
Vegetation here is characteristic of the plains: prickly pear and pincushion cacti, bluebunch wheatgrass, big sagebrush, saltbush, and buckwheat brush.
The headwaters area is also a popular fishing spot.