U.S. Route 12 (US 12) in the U.S. state of Illinois is an arterial highway that runs northwest to southeast through the Chicago metropolitan area. It enters Illinois at the Wisconsin border north of Richmond, and exits into Hammond, Indiana from Chicago near the foot of the onramp to the Indiana Toll Road (Interstate 90, I-90); as it exits Illinois, the route is also concurrent with US 20 and US 41. Within Illinois, US 12 runs for a distance of . Route description Richmond to Des Plaines The westernmost portion of US 12 in Illinois runs south from the Wisconsin border, between Genoa City, Wisconsin and Richmond. North of Genoa City, US 12 is a four-lane limited-access freeway. In Illinois, it reverts to a two-lane, undivided surface road prior to a traffic light with Illinois Route 173 (IL 173) north of Richmond. South of Richmond, through traffic on US 12 must turn left at IL 31 to continue. Until the Fox Lake area; at that point it becomes a four-lane divided highway, with occasional interchanges. US 12 runs concurrently with IL 59 south of Fox Lake at an access-controlled interchange, and then intersects with IL 134 at a traffic light. In Volo, there is a traffic light with IL 120, but then reverts to an expressway, with interchanges for IL 176 (Liberty Street) and IL 59. From the state line to this point, US 12 is also marked as the main route for the Fox River Valley, which continues south on IL 59. In Lake Zurich, US 12 picks up the name Rand Road, named so for a former name of the city of Des Plaines. There is also an intersection with IL 22 (Main Street). US 12 proceeds towards Deer Park and Kildeer before entering Cook County in Palatine. US 12 then briefly overlaps IL 53 between Hicks Road and IL 68 (Dundee Road) in northeast Palatine. At the expressway portion of IL 53, US 12 traffic can only access southbound IL 53. From IL 53, US 12 travels through the heavily populated areas of Arlington Heights and Mount Prospect, intersecting with IL 83 (Elmhurst Road) in Mount Prospect. US 12 enters the Des Plaines area at IL 58 (Golf Road), and joins with US 45 (Des Plaines River Road) north of downtown at a complex intersection. Westbound US 12 traffic is required to cross US 45 twice (on