IL 390 begins at an interchange with US 20 in Hanover Park and branches off northeastward as a six-lane toll road, traveling over a half-mile-long (0.8 km) bridge over the Metra Milwaukee District West Line tracks, and some wetlands.

[citation needed] Although Lake Street was extensively widened prior to the completion of the highway, initially to Glen Ellyn Road and then to the Roselle-Bloomingdale border nearly ten years later, its capacity was still considered insufficient for the rapidly growing western suburbs.

[citation needed] According to the Illinois Department of Transportation (IDOT), average daily traffic counts (in 2003) for IL 390 are 39,600 vehicles for the western two miles (3.2 km) and around 82,000 to 87,000 cars per day for the remainder.

[4] On October 29, 2013, IDOT announced that the highway was re-designated IL 390 at groundbreaking ceremonies for the Elgin–O’Hare Western Access Project.

[5] ISTHA began constructing an eastward extension of IL 390 to a new interchange on the western border of O'Hare International Airport with the planned I-490 connecting I-90 to the north and I-294 to the south.

[3] The first four miles (6.4 km) segment of this extension, opened at a ribbon-cutting ceremony on November 1, 2017, stretching from the interchange with I-290 in Itasca to IL 83 in Bensenville.