Originally known as the "East-West Tollway" in the Chicago area, and originally holding a local designation of Illinois State Route 5, the entire stretch became known as Interstate 88 during the 1980s when the route was connected to Interstate 80, near the Illinois/Iowa border.

The road is officially a tollway east of the Sterling/Rock Falls area, east of the intersection with U.S. Highway 30. It ends at the Interstate 290/Interstate 294 intersection near Hinsdale. West of U.S. 30 to Interstate 80, Interstate 88 is a freeway. The tollway portion is 96 miles (154 km) long.

Illinois State Route 56 is a part of the tollway between Illinois State Route 31 and Sugar Grove. This is partially because that was the original routing of Illinois 56, and partially because both roads have to get over the Fox River somehow.

In 2004, after the death of Ronald Reagan, the Illinois State Toll Highway Authority voted to rename the toll roadway to the Ronald Reagan Memorial Tollway.