Illinois Route 59 is a north–south state highway in northeastern Illinois. It runs south from Illinois Route 83 in Antioch to I-55 in Shorewood, spanning the north–south width of Chicago's western suburbs. This is a distance of 71.13 miles (114.47 km).

Illinois 59 is a major four-lane arterial for most of its length, running parallel to and about five miles (8 km) east of the Fox River in Illinois. It is especially crowded in the suburbs of Naperville, West Chicago, and Plainfield. Most of Illinois 59 in that area is zoned commercially for about 5 miles (8 kilometers). Illinois 59 is the only numbered highway with a Metra station named after it on the BNSF line; this name differentiates the station from the main Naperville station further east on the line.

Illinois 59 is called Sutton Road in the vicinity of U.S. Route 20 (Lake Street) and Illinois Route 19 (Irving Park Road). Route 59 is called Neltnor Blvd. in the vicinity of Illinois Route 64 (North Avenue). Illinois Route 59 is known as Barrington Rd./Hough St. through Barrington. In the Shorewood area, Route 59 is known as Cottage St. and Brookforest Ave.

Between Interstate 90 (the Northwest Tollway) and West Chicago, Illinois 59 runs through Hoffman Estates, Streamwood and Bartlett.

Illinois 59 overlaps U.S. Route 12 (Rand Road) between Wauconda and Fox Lake.

SBI Route 59 ran from Joliet to Antioch on the current Illinois 59. Illinois 59 was replaced by U.S. Route 66 as U.S. 66 made its way onto a new highway in 1940; by 1957, Illinois 59 had been returned to its original state.

In almost every town or village spanning Route 59, retail development and sprawl can be found. The main shopping areas are Warrenville/Naperville/Aurora, West Chicago/Bartlett, Streamwood, and Hoffman Estates/South Barrington. Westfield Fox Valley in Aurora, Poplar Creek Crossing in Hoffman Estates, and The Arboretum of South Barrington can all be found along the Route 59 corridor.