The Ohio River and the Illinois River join the Mississippi River in Illinois.
The Missouri River flows into the Mississippi River just north of Saint Louis, Missouri.
The Mississippi River is the western border of Illinois separating Illinois from Iowa and Missouri.
Mississippi River
Ohio River
At Cairo, Illinois, the Ohio joins the Mississippi. The three states that have borders there are Illinois (to the NE), Kentucky (to the SE) and Missouri (to the W).
The Lower Mississippi River begins in Cairo, Illinois where the Upper Mississippi River and the Ohio River meet. The Lower Mississippi flows out to the Gulf of Mexico.
Cairo, Illinois at the confluence of the Ohio River
The Mississippi River forms the boundary between Illinois and Missorui
Illinois is bordered by the Mississippi River on the west.
Illinois borders the Mississippi River to the west.
The Mississippi River borders Illinois on the west.
A number of rivers merge with the Mississippi, most notably the Missouri, the Illinois, the Ohio, the the Arkansas, and the Red.
The Mississippi River.
The Mississippi River.
Rivers flow in any direction they choose, constantly shifting and changing course in their search for a lower elevation.