Illinois has a rich history that dates back thousands of years, beginning with Native American tribes such as the Pottawatomie, Illiniwek, and Kickapoo. European exploration began in the 17th century, with French explorers like Jacques Marquette and Louis Jolliet mapping the region. Illinois became a U.S. territory in 1809 and achieved statehood in 1818. Throughout the 19th century, Illinois grew rapidly due to its fertile land and strategic location. The arrival of the Illinois Central Railroad in the 1850s boosted its economy, while cities like Chicago emerged as major urban centers. Illinois played a significant role in the Civil War and became known for its contributions to agriculture and industry.