Illinois was originally inhabited by several Native American tribes such as the Illini, Chickasaw, and Ho-Chunk. It was explored by French explorers in 1673 and was part of the French empire until 1763. Illinois became a U.S. state in 1818, the 21st state admitted. Today, Illinois has a large Polish American population, with over 930,000 Polish Americans residing in the state as of 2000, especially in Chicago and its surrounding suburbs.