The Missouri Territory was originally known as the larger
Louisiana Territory since 1804 (encompassing most of the 1803
Louisiana Purchase from the
French Empire) and was renamed by the
U.S. Congress on June 4, 1812, to avoid confusion with the new 18th
state of
Louisiana (further to the south on the lower
Mississippi River with its river port city of
New Orleans), which had been
admitted to the Union on April 30, 1812. On October 1, 1812, newly appointed fourth Territorial Governor
William Clark (1770–1838, served 1813–1820), organized the five administrative districts of the former
Louisiana Territory into the first five
counties of the then new Missouri Territory. The
Anglo-American Convention of 1818 established the northern boundary of the six years old Missouri Territory with the adjacent
British North America (future
Dominion of Canada) territory of
Rupert's Land at the
49th parallel north of latitude. This gave the Missouri Territory the
Red River Valley (
Red River of the North), south of the 49th parallel and gave to Rupert's Land that slice of upper
Missouri River Valley north of the 49th parallel. The
Adams–Onís Treaty of 1819, between the
Kingdom of Spain and the
United States, established the southern and western boundaries of the old
Louisiana Purchase territory of 1803, with the Royal Spanish territories of
Spanish Texas and
Santa Fe de Nuevo México. As a result of the protracted negotiations, the United States surrendered a significant portion of the Missouri Territory claimed in the southwest to
Spain in exchange for the peninsula of
Spanish Florida further east. The
Convention of 1818 and the subsequent
Adams–Onís Treaty the following year, would be the last significant losses of United States claimed territories from the continental
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 the
Kingdom of Spain in 1819 would be re-taken by the U.S. by force, following the
Annexation of Texas Republic (1845) and the
Mexican–American War, (1846–1848), along with the
Mexican Cession of territories further west of 1849. On March 2, 1819, all of the Missouri Territory directly south of the
parallel 36°30' north, except the so-called
Missouri Bootheel between the
Mississippi River and the
Saint Francis River north of the
36th parallel north, was designated the new federal
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 remaining Missouri Territory was admitted to the Union as the 21st
State of Missouri on August 10, 1821.
St. Louis on the west bank of the
Mississippi River was the
capital of the Missouri Territory. The remaining portion of the territory to the north, northwest, west and southwest, consisting of the present states of
Iowa,
Nebraska, and
the Dakotas, most of
Kansas,
Wyoming,
Montana, and parts of
Colorado,
Minnesota and
New Mexico, effectively became reverted to the status of
unorganized territory after 1821, when Missouri became the 21st state. Thirteen years later in 1834, the portion in the north and east of the upper
Missouri River was attached to the
Michigan Territory around the
Great Lakes. Over time, various
federal territories in
the West were created in whole or in part from its remaining area of unorganized status, as follows:
Indian Territory (1834), added with future
Oklahoma (1890),
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 old Missouri Territory reported the following population counts: == See also ==