The Vermilion River is a tributary of the Wabash River located in the state of Illinois, United States.
There are two "Vermilion Rivers" in Illinois. The Wabash tributary flows south. The other Vermilion River flows north. See Vermilion River (Illinois River tributary). There is also at least one Little Vermilion River.
The north-flowing Vermilion River and the south-flowing Middle Fork Vermilion River lie along a straight line connecting Oglesby and Danville. The two rivers drain what was once an upland marsh near Roberts. The two Rivers have been extended by drainage ditches so that they nearly connect at their headwaters. The Rivers may share a common name because early settlers regarded them as a single river that flowed two directions. The Rivers may have served as a canoe route between the Illinois River and Wabash River, with a portage through the marshes near Roberts.
