What is illinois-indiana border river?

The Illinois-Indiana border river is the Wabash River. It stretches for about 475 miles from its headwaters near Fort Recovery, Ohio, to its confluence with the Ohio River near the town of Shawneetown, Illinois. The Wabash River is the longest river in Indiana and the state's official river. It forms part of the boundary between Indiana and Illinois for roughly 215 miles, beginning around Terre Haute, Indiana. The Wabash River is a major tributary of the Ohio River and drains an area of about 33,000 square miles. It is also an important transportation route and recreational resource for the region.