Louisiana−Missouri Territory: Polity Style: 1804-1820

21 Oct 1803	part of the territory of North America known as Louisiana, legally claimed by France and administered by Spain, is ceded by France to the United States in accordance with a treaty and conventions concluded in Paris by representatives of both nations on 30 Apr 1803, effective upon the exchange of ratifications in Washington, D.C., on 21 Oct 1803 (Martens, 7:706-727; Clercq, 2:59-66; Territorial Papers, 9:81-82)
20 Dec 1803	Louisiana is transferred to the United States in accordance with an instrument of transfer signed by commissioners of the governments of France and the United States in New Orleans on 20 Dec 1803 (American State Papers, Foreign Relations, 2:582)
9 Mar 1804	Upper Louisiana is transferred from Spain to France in accordance with a deed of transfer signed by Lieutenant General of Upper Louisiana and commissioner of France in St. Louis on 9 Mr 1804 (Billon, pp. 360-361)
10 Mar 1804	the government of Upper Louisiana is assumed by a commandant on behalf of the United States in St. Louis on 10 Mar 1804 (Transfer of Upper Louisiana, pp. 86-92)
1 Oct 1804	Louisiana is divided into two territories—the Territory of Orleans and the District of Louisiana—in accordance with an act passed by the Congress of the United States (Senate on 18 Feb 1804, House of Representatives on 17 Mar 1804), signed into law on 26 Mar 1804, effective on the date (1 Oct 1804) prescribed by Sec. 16 of the said act (Statutes at Large, 2:283-289) [1]
1 Oct 1804 - 3 Jul 1805	District of Louisiana [2]
4 Jul 1805	the District of Louisiana is constituted as a territory of the United States under the name of the Territory of Louisiana, in accordance with an act passed by the Congress of the United States (Senate on 1 Mar 1805, House of Representatives on 2 Mar 1805), signed into law on 3 Mar 1805, and made effective on 4 Jul 1805 as provided by Sec. 10 of the said act (Statutes at Large, 2:331-332) [3]
4 Jul 1805 - 6 Dec 1812	Territory of Louisiana
7 Dec 1812	the name of the territory is changed to the Territory of Missouri in accordance with an act passed by the Congress of the United States (House of Representatives on 9 Apr 1812, Senate on 19 May 1812 with amendments, the amendments are concurred in by the House on 21 May 1812), signed into law on 4 Jun 1812, effective on 7 Dec 1812 as provided by Sec. 16 of the said act (Statutes at Large, 2:743-747) [4]
7 Dec 1812 - 17 Sep 1820	Territory of Missouri
4 Jul 1819	the southern portion of the Territory of Missouri is constituted as a separate territory of the United States under the name of the Arkansaw territory in accordance with an act passed by the Congress of the United States (House of Representatives on 20 Feb 1819, Senate on 1 Mar 1819), signed into law on 2 Mar 1819, effective on 4 Jul 1819 (Statutes at Large, 3:493-496) [5]
6 Mar 1820	the inhabitants of the southeastern portion of the Territory of Missouri are authorized to form a constitution for further admission to the Union in accordance with an act passed by the Congress of the United States (House of Representatives on 1 Mar 1820, Senate on 2 Mar 1820 with amendments, the amendments are concurred in by the House on 2 Mar 1820), signed into law on 6 Mar 1820 (Statutes at Large, 3:545-548) [6]
19 Jul 1820	the Constitution of the State of Missouri is adopted by the Convention on 17 Jul 1820, signed by the members of the Convention on 19 Jul 1820 and came into operation on 18 Sep 1820 (Missouri Convention 1820, p. 46) [7][8]

Full title: An Act erecting Louisiana into two territories and providing for the temporary government thereof.
Executive and legislative authority in the District of Louisiana was vested in the Governor of the Indiana Territory.
Full title: An Act further providing for the government of the district of Louisiana.
Full title: An Act providing for the government of the territory of Missouri.
Full title: An Act for the admission of the State of Arkansas into the Union, and to provide for the due execution of the laws of the United States, within the same, and for other purposes.
Full title: An Act to authorize the people of the Missouri territory to form a constitution and state government, and for the admission of such state into the Union on an equal footing with the original states, and to prohibit slavery in certain territories.
After the Constitution of the State of Missouri went into effect, the remaining portion of the Territory of Missouri became an unorganized territory of the United States.
The Constitution did not include a clause fixing the date when it would come into operation, but Section 1 of the Schedule declared that "all writs, actions, prosecutions, judgments, claims, and contracts, of individuals, and of bodies corporate, shall continue as if no change had taken place; and all process which may, before the third Monday in September next, be issued under the authority of the Territory of Missouri, shall be as valid as if issued in the name of the state." The General Assembly of the State of Missouri met on 18 Sep 1820 and Alexander McNair was sworn in as the Governor of the State on 19 Sep 1820 before the Constitution was approved by the Congress of the United States.