What European country once owned Illinois?

Answer 1

Both the French and the British owned Illinois at one point. It was part of the Ohio River Valley, which was given to the British after they won the French and Indian War (it later became part of the United States when they achieved independence from the British). You can especially see the French influence in the name of Illinois, since it is a French word.

Answer 2

Illinois was once owned by France. French explorers and fur traders were the first Europeans to establish a presence in the region during the 17th century. Illinois remained under French control until it was ceded to Great Britain in 1763 after the French and Indian War.