The State of Tennessee is south of the State of Illinois.
Mississippi River
The Mississippi River forms the western border of Illinois.
Mississippi.
Mississippi river
Missouri is north, and very slightly east of Arkansas. Kentucky and Illinois are actually northeast, but don't border Arkansas.
Illinois has the longest common border with Missouri.
Illinois.
Ohio
Michigan, Ohio, Illinois and Kentucy are the states that border Indiana.
The state of Illinois is bordered on the north by the state of Wisconsin. Illinois also shares borders with Iowa to the northwest, Missouri to the west, Kentucky to the southeast, and Indiana to the east. In the northeastern part of the state, Illinois borders Lake Michigan where Chicago is located.
The US State of Illinois and the US State of Kentucky share a border with the Ohio River that runs between the two States. There is no land border with each other.