Indians hunted Illinois as far back as 5,000 B.C., and today, still visible, are the remains of their civilization at places like Cahokia Mounds-North America's largest and most valuable prehistoric earthenwork relic.
The first European explorers in Illinois were Jacques Marquette and Louis Joliet, Frenchmen who paddled by birchbark canoe along the Mississippi and Illinois Rivers. They traveled the virtual length of the state-from what is now Chicago to the southernmost reaches of Illinois.
More French explorers followed, building military outposts and establishing a fur trading empire with local Indians. In 1763, at the close of the French and Indian War, the Treaty of Paris ceded to England all the lands France had claimed east of the Mississippi River, except for New Orleans in Louisiana.
The British continued to control what is now Illinois until 1778 when George Rogers Clark, a Revolutionary War hero, and his band of American colonists captured Fort Kaskaskia. The Illinois country became a possession of Virginia until 1787 when it joined the Northwest Territory under the government of the United States. Kaskaskia became Illinois' first Capital in 1818. Two years later the seat of Illinois government was moved to Vandalia. In 1839, largely through the efforts of a young legislator named Abraham Lincoln, the Capital was again moved--this time to Springfield, where it remains.
Source: State of Illnois.