Missouri Headwaters State Park
[2] The park includes the Three Forks of the Missouri National Historic Landmark, designated in 1960 because the site is one where the Lewis and Clark Expedition camped in 1805.Lewis and Clark were at first uncertain how to proceed, and scouted each of the branches before ultimately departing on July 30 up the Jefferson River.If the Jefferson were included in the Missouri length, it would technically still be considered the longest river by experts of the United States Geological Survey.The utmost headwaters of the Missouri are subject to debate but two commonly claimed locations ultimately drain into the Jefferson.Lewis on August 12, 1805 said he visited the headwaters on Trail Creek just above Lemhi Pass on the Continental Divide in the Beaverhead Mountains at around 8,600 feet which he described: In 1888 Jacob V. Brower, who had championed turning the headwaters of the Mississippi River into a Minnesota state park, visited another site which today is also claimed to be the furthest point on the Missouri.