Illinois became a state on Dec. 3, 1818. The state was the 21st one to entire the union. At the time of statehood, only 35,000 Americans resided on its lands, challenged by the region's vegetation and soil. This population was 25,000 short of the minimum typically needed to grand statehood.
The Northwest Ordinance of 1787 mapped the region and established counties, and 22 years later, in 1809, Illinois became an official territory of the United States. Before statehood, however, Illinois representatives persuaded Congress to move the territory's border 51 miles north so that Chicago would be included in the state. The first capital of the state was Kaskaskia.