Illinois Route 6 is a 4-lane freeway in central Illinois. It begins as a northern extension of Interstate 474 at Interstate 74 west of Peoria, and ends at Illinois Route 29 in Mossville, south of Chillicothe. The freeway currently has a total length of 10.11 miles (16.27 km), including the connector ramp to Illinois 29.

Although fairly short, Illinois 6 draws more traffic than a rural highway because it passes through the developing north and northwest edge of Peoria. A one-mile (1.6 km) stretch of road around the U.S. Route 150 (War Memorial Drive) exit has become a major commercial development area that now includes a major mall and a nearby strip mall with over 30 movie screens between them. In addition, new development is occurring rapidly around the other interchanges of Allen Road (old Illinois Route 174), Knoxville Avenue (Illinois Route 40), and Illinois Route 29.

Plans have been considered to either extend Illinois 6 into a loop by building a bridge over the Illinois River and running the highway south to Interstates 74 and 474 near Interstate 155 in Morton, or to build north or northeast from the current terminus to make Illinois 6 part of an often-proposed Peoria-to-Chicago Highway. As of 2009, plans are being considered for an eastern connection to loop the highway around to the current eastern end of Interstate 474 (which is the most heavily studied option) or the north end of Interstate 155. The possibility of another bridge over the Illinois River is still on the table. Recently, a Republican Illinois State Senator, Dale Risinger, has put forth a bill that would make the proposed route a toll road (it would likely cost drivers more to drive around another way than to have to pay the toll).

The entire route is in Peoria, Peoria County.