In the early nineteenth century, other than in the well-established state of Louisiana, most early settlement west of the Mississippi was centered on St. Louis. As the major center for trade and supplies for the lands to the west, St. Louis had grown to a city of over 10,000 citizens, with the region around steadily increasing in population as emigrants created new farms and towns.
In 1818, a petition was put forward to create a state of Missouri out of the southeastern part of the vast Missouri Territory. Slavery had been legal since the founding of the Missouri Territory, so the proposal was for the state of Missouri to come into the Union as a slave state. However, by this time the issue of slavery, and the expansion of slavery into newly formed states in the American West, had become a very controversial subject.
In 1818, there was a balance in Congress between the slave and free states and neither side was willing to give the other the advantage of a new state in their camp. Thus Northerners would not consider allowing Missouri to come in as a slave state without the simultaneous admittance of a free state. At this time, however, those in the District of Maine, then part of Massachusetts, were clamoring to be let in as a state, so in 1820 the compromise was reached that Maine would be admitted as a free state at the same time Missouri would come in as a slave state.
The Missouri Comprise also had another element which was important in the development of the American West, the prohibition of new slave states (other than Missouri) north of the 36.30 degree parallel line. This line was the northern border of North Carolina and Tennessee and it was considered something of a dividing line between the North and South. Northern Congressmen would allow Missouri, located above the line, to come in as a slave state, but were not interested in allowing any more slave states above that line.
So it was that in 1821, the southeastern part of the Missouri Territory was admitted as the state of Missouri. The western border was on a line run due north-south from the junction of the Kansas and Missouri Rivers, with the northern border coming off of this line 100 miles above the rivers' junction. If you look at a map of Missouri today, the north western part of the state is not a straight north-south line, for the Platte Purchase of 1835 added to the state what in 1821 was still Indian territory.
In 1821, the rest of the old Missouri Territory became officially unorganized U.S. Territory and it was essentially territory claimed by various Indian tribes. Meanwhile, the U.S. Government was busy trying to move eastern Indian tribes to west of the Mississippi, including the Choctaw, who by the 1820 Treaty of Doak’s Stand, were given land in what was then the western part of Arkansas Territory.
In 1824, in order to separate the Choctaw and other tribes’ lands from the Euro-American settlements in eastern Arkansas, the Arkansas Territory was essentially cut in half, with the new western border starting at a point 40 miles west of the southwest corner of Missouri, and then running due south to the Red River. However, this meant that much of the Choctaw lands was still within the Arkansas Territory and the Choctaw were not ready to give up this territory.
After considerable negotiation (some of it likely more intimidation), the Choctaw agreed to move a bit further west. The United States wanted the new western border to run straight south from the southwest corner of Missouri, but the Choctaw insisted on their land extending to within 100 paces west of the Fort Smith, so the final border ran slightly southeast from the corner of Missouri to just west of Fort Smith and from thence due south.
The boundary changes in the decade from 1820 to 1829 where not many—-the creation of the state of Missouri and the truncating of the Arkansas Territory-—but the Missouri Compromise would continue to reverberate in the history of the American West in the decades to come. The story of the development of the American West continues in the next blog in this series.