Lewis at the Marias

In the summer of eighteen oh six, on the return leg of the great expedition, Meriwether Lewis split from William Clark and took just three men north to explore the Marias River. President Jefferson wanted to know whether this branch reached north of the forty-ninth parallel, because if it did, it would stretch the boundary of the new Louisiana Purchase and hand the young United States more of the rich fur country.

Lewis pushed up the Marias to about this point in late July, only to find the river bending away to the west, well short of where he had hoped. Disappointed, he named his northernmost camp nearby Camp Disappointment. The detour turned deadly days later, when a clash with Blackfeet warriors left two of them dead and became the only violent encounter of the entire journey. Then Lewis hurried south to rejoin Clark and bring the expedition home.