Missouri Territory is Established: June 4, 1812

Missouri Territory, comprised of all of the land that made up the Louisiana Purchase in 1804 except for the newly admitted state of Louisiana, was officially established by an act of congress on this date. The establishment amounted to little more than a renaming. Before Louisiana’s admission, the territory had all been called “Louisiana Territory.” Now, to avoid confusion with the name of the country’s newest state (Louisiana was admitted on April 12, 1812), the remaining incorporated territory was renamed Missouri Territory.

Territorial governor William Clark would divide the territory up into five counties later in the year, these forming the basis for the state’s original five counties, all of which still exist. They included Saint Louis County, Saint Charles County, Sainte Genevieve County, Cape Girardeau County, and New Madrid County.

Missouri Territory was affected by the establishment of new territories, such as Arkansas Territory, and by land cessions to both the British and Spanish in the nine years before Missouri became a state. Although the territory’s area would eventually go on to form states including Nebraska, Kansas, Iowa, Montana, and even part of Minnesota, for almost a decade it bore the name Jacques Marquette had given to its largest waterway in 1673, and which would ultimately become our state’s name.