Wilmington is located along the banks of the Kankakee River and follows the original 1926 route of Illinois Route 66. A distinguishing feature of Wilmington is a large island in the Kankakee River that divides the river into a wider channel and a narrower one. This unique characteristic has earned the city the nickname "The Island City."

Spanning 14 square miles, Wilmington offers a welcoming blend of small-town charm and modern convenience.