Illinois shares borders with six states (and Lake Michigan / international water boundary with Michigan).
| State | Direction | Border Type | Length | Major Crossings |
|---|---|---|---|---|
| Wisconsin | North | Land (42°30' N parallel) | ~150 mi | I-94, I-90, US-41, US-12 |
| Indiana | East | Land (meridian) | ~160 mi | I-94, I-90, I-80, I-74, I-70, US-41, US-30 |
| Kentucky | Southeast / South | River (Ohio River) | ~130 mi | I-24, US-45, US-60, US-62, Shawneetown Bridge |
| Missouri | West / Southwest | River (Mississippi River) | ~350 mi | I-55, I-64, I-70, US-40, US-60, US-61, US-67, Clark, Poplar St, MLK, Stan Musial bridges |
| Iowa | Northwest | River (Mississippi River) | ~180 mi | I-80, I-74, US-6, US-30, US-61, US-67, US-150, Centennial, Rock Island, Savanna-Sabula bridges |
| Michigan | Northeast | Water (Lake Michigan) | ~60 mi (water) | Lake Michigan car ferry: Ludington (MI) ↔ Manitowoc (WI) — not direct to IL |