Why does I-180 in IL exist?
I-180 serves the town of Hennepin, population 707 (2000 census). It was built to serve LTV steel, a major defense contractor. In the future it may be extended south to Peoria, signed either as I-180 or IL-29 ( http://www.dot.il.gov/il29/default.aspx ), but it currently has almost no traffic. See http://www.kurumi.com/roads/3di/i180.html#180il , http://www.n9jig.com/gallery/expw.html , and http://www.interstate-guide.com/i-180_il.html .