Territory of Missouri
Organized incorporated territory of United States
Flag of Missouri

Map of the Territory of Missouri in 1812
CapitalSt. Louis
 • TypeOrganized incorporated territory
• Renaming of Louisiana Territory
June 4 1812
• Territory of Arkansas created
March 2, 1819
• Missouri statehood
August 10 1821
Preceded by
Succeeded by
Louisiana Territory
Territory of Arkansas
Unorganized territory
Indian Territory
Rupert's Land
Missouri Territory, formerly Louisiana, 1814 map

The Territory of Missouri was an organized incorporated territory of the United States that existed from June 4, 1812,[1] until August 10, 1821. In 1819, the Territory of Arkansas was created from a portion of its southern area. In 1821, a southeastern portion of the territory was admitted to the Union as the State of Missouri, and the rest became unorganized territory for several years.


The Missouri Territory was originally known as the Louisiana Territory and was renamed by the U.S. Congress on June 4, 1812, to avoid confusion with the new state of Louisiana, which had been admitted to the Union on April 30, 1812.

On October 1, 1812, Governor Clark organized the five administrative districts of the former Louisiana Territory into the first five counties of the Missouri Territory.

The Anglo-American Convention of 1818 established the northern boundary of the Missouri Territory with the British territory of Rupert's Land at the 49th parallel north. This gave the Missouri Territory the Red River Valley south of the 49th parallel and gave Rupert's Land the slice of Missouri River Valley north of 49th parallel. The Adams–Onís Treaty of 1819 established the southern and western boundaries of the territory with the Spanish territories of Spanish Texas and Santa Fe de Nuevo México. The United States surrendered a significant portion of the Missouri Territory to Spain in exchange for Spanish Florida. The Convention of 1818 and the Adams–Onís Treaty would be the last significant losses of United States territory from the contiguous United States, although the cession of lands north of the 49th parallel would turn out to be the only permanent cession of U.S. territory (the territories ceded to Spain would be re-taken by the U.S. following the Texas annexation and the Mexican–American War).

On March 2, 1819, all of the Missouri Territory south of the parallel 36°30' north, except the Missouri Bootheel between the Mississippi River and the Saint Francis River north of the 36th parallel north, was designated the new Territory of Arkansaw. (The spelling of Arkansaw would be changed a few years later, although the proper pronunciation of the name would be debated until 1881.) The southeastern portion of the Missouri Territory was admitted to the Union as the State of Missouri on August 10, 1821.

St. Louis was the capital of the Missouri Territory.[2]

The remaining portion of the territory, consisting of the present states of Iowa, Nebraska, and the Dakotas, most of Kansas, Wyoming, and Montana, and parts of Colorado, Minnesota and New Mexico, effectively became an unorganized territory after Missouri became a state. In 1834, the portion east of the Missouri River was attached to the Michigan Territory. Over time, various territories were created in whole or in part from its remaining area: Iowa (1838), Minnesota (1849), Kansas and Nebraska (both 1854), Colorado and Dakota (both 1861), Idaho (1863), Montana (1864), and Wyoming (1868).

In the 1820 United States census, 15 counties in the Missouri Territory reported the following population counts:[3]

Rank County Population
1 Howard 13,426
2 St. Louis 10,049
3 Cooper 6,959
4 Cape Girardeau 5,968
5 Ste. Genevieve 4,962
6 St. Charles 3,970
7 Pike 3,747
8 Montgomery 3,074
9 Washington 2,769
10 Franklin 2,379
11 New Madrid 2,296
12 Madison 2,047
13 Jefferson 1,835
14 Lincoln 1,662
15 Wayne 1,443
Missouri Territory 66,586

See also


  1. ^ Stat. 743
  2. ^ "How the City of Jefferson became the State Capital". Archived from the original on February 7, 2005. Retrieved July 9, 2011.
  3. ^ Forstall, Richard L. (ed.). Population of the States and Counties of the United States: 1790–1990 (PDF) (Report). United States Census Bureau. pp. 93–95. Retrieved May 18, 2020.