Louisiana-Missouri Territory: Governors: 1805-1820

Governor of the Territory of Louisiana [1]
4 Jul 1805 - 3 Mar 1807	James Wilkinson [2]
Secretary, exercising the Government, and the office of Commander-in-Chief of the Territory of Louisiana [3]
3 Mar 1807 - 7 Apr 1807	Joseph Browne [4]
7 Apr 1807 - 8 Mar 1808	Frederick Bates [5]
Governor of the Territory of Louisiana
8 Mar 1808 - 11 Oct 1809	Meriwether Lewis [6]
Secretary, exercising the Government, and the office of Commander-in-Chief of the Territory of Louisiana [3]
11 Oct 1809 - 17 Sep 1810	Frederick Bates [7]
Governor of the Territory of Louisiana and Commander-in-Chief of the Militia thereof
17 Sep 1810 - 6 Dec 1812	Benjamin Howard [8]
Governor of the Territory of Missouri and Commander-in-Chief of the Militia thereof
7 Dec 1812 - 18 Apr 1813	Benjamin Howard
Secretary of the Territory of Missouri, and exercising the Government
18 Apr 1813 - 6 Jul 1813	Frederick Bates
Governor of the Territory of Missouri, and Commander-in-Chief of the Militia thereof
6 Jul 1813 - 17 Sep 1820	William Clark [9][10]

The commissions issued for the appointment of Wilkinson in 1805 and 1806 referred to the office as Governor in and over the Territory of Louisiana. Also in official use: Governor and Superintendent of Indian affairs in and over the Territory of Louisiana, Governor and Commander-in-Chief in and over the Territory of Louisiana.
Wilkinson was commissioned as governor on 11 Mar 1805 with the term commencing on 3 Jul 1805 and took the oath of office in the County of Randolph, Indiana Territory, on 27 Jun 1805. However, the Territory of Louisiana was constituted on 4 Jul 1805. Wilkinson left the Territory, departing from St. Louis on 16 Aug 1806, but continued in office to the date of commencement of the term of his successor (3 Mar 1807) and was, accordingly, paid up to 2 Mar 1807 (Territorial Papers, 14:3-5).
Also in official use: Secretary of the Territory of Louisiana, and exercising the Government thereof.
Acting for the absent incumbents: 16 Aug 1806 - 7 Apr 1807.
Pending the taking office of Meriwether Lewis.
Lewis was appointed Governor for a term ending on 3 Mar 1810 and took office on 8 Mar 1808. He departed for Washington, D.C., on 4 Sep 1809 and died during his travel on 11 Oct 1809.
Acting for the absent incumbent: 4 Sep 1809 - 11 Oct 1809.
Howard was commissined as governor on 18 Apr 1810 for a term ending on 18 Apr 1813. He arrived in St. Louis on 17 Sep 1810.
Clark was commissioned as governor on 16 Jun 1813. He arrived to St. Louis on 1 Jul 1813 and took the oath of office on 6 Jul 1813.
Following the adoption of the Constitution of the State of Missouri, all officers civil and military, holding commissions under the authority of the United States or of the Territory of Missouri, were authorized by a provision of the Constitution to continue in office until superseded.