The 1818 Treaty of St. Louis formalized the Osage Nation's cession of lands between the Arkansas and Verdigris Rivers to the United States.
Key Facts
- Date signed
- September 25, 1818
- Location
- St. Louis, Missouri
- US negotiator
- William Clark
- Ceding party
- Osage Nation
- Southern boundary
- Arkansas River at Frog Bayou
- Northern boundary
- 20 leagues north of the Arkansas River
Location
Cause → Event → Consequence
The Osage Nation faced repeated demands for restitution of property taken from US citizens by Osage war parties. Their chiefs had been unable to recover and return the property, and deductions from their annuities under the 1808 Fort Clark treaty threatened to leave them without funds for years, creating pressure to resolve the debt through a land cession.
On September 25, 1818, William Clark representing the United States and delegates of the Osage Nation signed the Treaty of St. Louis in St. Louis, Missouri. The Osage formally ceded to the United States all territory bounded by the Arkansas River at Frog Bayou, running up to the falls of the Verdigris River, then eastward to a point twenty leagues north of the Arkansas River.
The Osage Nation permanently relinquished its claim to the described tract, expanding US territorial control in the region that would become part of present-day Arkansas and Oklahoma. The cession resolved the outstanding financial obligations the Osage owed under the 1808 Fort Clark treaty and further diminished Osage territorial holdings in the lower Missouri and Arkansas region.
Political Outcome
The Osage Nation ceded lands between the Arkansas and Verdigris Rivers to the United States, resolving outstanding debt obligations under the 1808 Fort Clark treaty.
Osage Nation held territorial claims to lands between the Arkansas and Verdigris Rivers
United States assumed full sovereignty over the ceded territory