Indiana Territory replaces Northwest Territory
The Indiana Territory, officially the Territory of Indiana, was created by an organic act that President John Adams signed into law on May 7, 1800, to form an organized incorporated territory of the United States that existed from July 4, 1800, to December 11, 1816, when the remaining southeastern portion of the territory was admitted to the Union as the state of Indiana. The territory originally contained approximately 259,824 square miles (672,940 km2) of land, but its size was decreased when it was subdivided to create the Michigan Territory (1805) and the Illinois Territory (1809). The Indiana Territory was the first new territory created from lands of the Northwest Territory, which had been organized under the terms of the Northwest Ordinance of 1787. The territorial capital was the settlement around the old French fort of Vincennes on the Wabash River, until transferred to Corydon near the Ohio River in 1813.
William Henry Harrison, the territory's first governor, oversaw treaty negotiations with the Native inhabitants that ceded tribal lands to the U.S. government, opening large parts of the territory to further settlement. In 1809 the U.S. Congress established a bicameral legislative body for the territory that included a popularly-elected House of Representatives and a Legislative Council. In addition, the territorial government began planning for a basic transportation network and education system, but efforts to attain statehood for the territory were delayed due to war. At the outbreak of Tecumseh's War, when the territory was on the front line of battle, Harrison led a military force in the opening hostilities at the Battle of Tippecanoe (1811) and in the subsequent invasion of Canada during the War of 1812. After Harrison resigned as the territorial governor, Thomas Posey was appointed to the vacant governorship, but the opposition party, led by Congressman Jonathan Jennings, dominated territorial affairs in its final years and began pressing for statehood.
In June 1816 a constitutional convention was held at Corydon, where a state constitution was adopted on June 29, 1816. General elections were held in August to fill offices for the new state government, the new officeholders were sworn into office in November, and the territory was dissolved. On December 11, 1816, President James Madison signed the congressional act that formally admitted Indiana to the Union as the nineteenth state.History
The area that became the Indiana Territory was once part of the Northwest Territory, which the Congress of the Confederation formed under the terms of the Northwest Ordinance on July 13, 1787. This ordinance outlined the basis for government in the western lands and also provided for an administrative structure to oversee the territory, including a three-stage process for transitioning from territory to statehood. In addition, the Land Ordinance of 1785 called for the U.S. government to survey the newly-acquired territory for future sale and development. The Northwest Territory, which initially included land bounded by the Appalachian Mountains, Mississippi River, Great Lakes, and Ohio River, was subsequently partitioned into smaller territories that included the Indiana Territory (1800), Michigan Territory (1805), the Illinois Territory (1809), and eventually became the present-day states of Ohio, Michigan, Indiana, Illinois, Wisconsin, and eastern Minnesota.