Arkansas Territory
Arkansas Territory was created out of the southern part of Missouri Territory in 1819. The border was established at parallel 36°30' north with the exception of the Missouri Bootheel. Arkansas Territory thus included all of the present state of Oklahoma south of this latitude. When Missouri achieved statehood in 1821, the territorial lands not included within the state's boundaries effectively became an unorganized territory. On November 15, 1824, the westernmost portion of Arkansas Territory was removed and included with the unorganized territory to the north, and a second westernmost portion was removed on May 6, 1828, reducing Arkansas Territory to the extent of the present state of Arkansas. This new western border of Arkansas was originally intended to follow the western border of Missouri due south to the Red River. However, during negotiations with the Choctaw in 1820, Andrew Jackson unknowingly ceded more of Arkansas Territory to them than was realized. Then in 1824, after further negotiations, the Choctaw agreed to move farther west, but only by "100 paces" of the garrison on Belle Point. This resulted in the bend in the Arkansas/Oklahoma border at Fort Smith, Arkansas.