26 Mar. 1749–21 Mar. 1800
During the first stage of the territory's history, Blount had autocratic authority. He proclaimed laws, created new counties, and appointed civil officials. Blount did not call a territorial legislature into session for over three years after his initial appointment. By 1794, the population was sufficient for the election of a territorial assembly, which in its first session chartered three colleges; one of these, the forerunner of the University of Tennessee, was named Blount College in honor of the governor. When a territorial census revealed a population adequate for statehood, Blount arranged for a constitutional convention, over which he presided as chairman, which drafted the state's first constitution. He was then elected as one of the state's first two members of the U.S. Senate.
His political career was mired by the Expulsion Case of William Blount of Tennessee (1797). A rumor that Spain was about to cede New Orleans and the Louisiana country to France is alleged to have started the affair. The alleged land cession would deny the Americans the right to use the Mississippi River for the export of their surplus products. Blount therefore took over the leadership of a scheme, already being developed, to organize an expedition of frontiersmen and Indians to help the British, then at war with Spain and France, take New Orleans, Louisiana, and Florida away from Spain. Great Britain was bound by the treaty of peace of 1783 to permit free navigation of the Mississippi River by Canadians and Americans. Before the plan could be put in operation, a letter Blount had written about it fell into the hands of federal authorities, namely President John Adams, and as a result he was expelled from the Senate. He was also impeached by the House of Representatives but was acquitted in trial before the Senate, because of lack of jurisdiction. Blount remained popular in Tennessee, where he was elected to the state senate and its speakership. He did not run for reelection and was out of office at the time of his death.
On 12 Feb. 1778, Blount married Mary Molsey Grainger, the daughter of Caleb Grainger of the Cape Fear region of North Carolina. They had seven children: Cornelius, Ann, Mary Louisa, William Grainger, Richard Blackledge, Barbara, and Eliza. Mary died around March 10, 1800, and William died soon on March 21 of the same year. They both died at the Blount Mansion in Knoxville are buried in the churchyard of the First Presbyterian Church, Knoxville, Tennessee. A marble slab marks his grave.