Within the boundaries of this scenic park and National Historic Landmark, the Jefferson, Madison, and Gallatin rivers merge to form the 2,300 mile Missouri River.

Considering it an essential point in the geography of this western part of the continent, Meriwether Lewis wrote the country opens suddenly to extensive and beautiful plains and meadows which appear to be surrounded in every direction with distant and lofty mountains. The legendary Sacajawea was captured here as a child and eventually returned as a member of the Corps of Discovery. Another member of this expedition, John Colter, later made several trips to this area in search of furs and began his famous run nearby. Pioneers slowly settled the surrounding area and transformed it into profitable grazing and farming land. Missouri Headwaters State Park preserves much of the region's abundant wildlife, lush, vegetation, and scenic beauty that have attracted people for thousands of years.

The park provides 17 campsites, tipi rental, foot trails to points of interest, and interpretive displays of the area's cultural and natural history. River floating, fishing, picnicking, bicycling, hiking, interpretive programs, and photography are popular activities.

The park is 532 acres in size and is 4,045 feet in elevation.