After George Rogers Clark captured the British strongholds at Kaskaskia, Cahokia, and Vincennes, Virginia claimed Illinois as a county in 1778. Because the large region was difficult to govern, Virginia ceded the county of Illinois to the federal government in 1784.
Thomas Jefferson proposed dividing the lands acquired from the British into fourteen regions.
Jefferson’s map of Southern Illinois included parts of Indiana and Kentucky, with its northern border near Vandalia. He named the region Polypotamia, meaning “land of many rivers”. Polypotamia would have appealed to settlers arriving from similar lands in Kentucky and would have enabled Southern Illinois to develop independently from the northern influence of Chicago, but neither this plan nor one that would have included the southern regions of Illinois and Indiana were accepted.
In 1787, the federal government included Illinois in the Northwest Ordinance that included Ohio, Indiana, Michigan, and Wisconsin. Illinois became a part of the Indiana Territory in 1800. Although fewer than two thousand European Americans lived in Illinois in 1800, settlers soon began to arrive from the mountainous regions of Kentucky, Tennessee, Virginia, Georgia, and the Carolinas.
In the familiar terrain of Illinois hill country, settlers found abundant lumber, fish, and game, and good soil for crops. They built log cabins with stone fireplaces for heating and cooking. Clothing was made of animal skins, linen, wool, or cotton. They supplemented their farm-based diet by hunting. Corn was the main crop and the woods provided nuts, berries, and other kinds of fruit. As more settlers arrived, they began providing schools for their children.
Illinois became a separate territory in 1809 as Illinois settlers sought more control over their own affairs.