The Tri-State Tollway is a US toll road maintained by the Illinois State Toll Highway Authority in northeastern Illinois. It is actually a combination of three different Interstates:

• Interstate 80 between Interstate 94 at Thornton and Interstate 294 at University Park
• Interstate 294, which is routed on top of Interstate 80 to University Park, and then turns north to Wheeling
• Interstate 94 north from Wheeling to Waukegan by the Wisconsin state line.

The segment containing Interstate 294 is 53 miles (85 km) long; in total, the Tri-State Tollway is actually about 78 miles (126 km) long. Only the Ronald Reagan Memorial Tollway is longer in length. The Tri-State Tollway does not enter either Indiana or Wisconsin.

Features

For being a relatively short highway, the Tri-State Tollway has numerous notable oddities.

• Over the road oases -- these oases are a part of the entire tollway system, but the most are on the Tri-State Tollway. They provide food and gas without having to exit the tollway proper.
• Thornton Quarry -- about .75 mile of the highway crosses a quarry being converted into a large lake for overflow storm water. See the Deep Tunnel project. Currently, the road's elevation over the floor of the quarry is up to 100 feet deep on both sides of the highway, making for a unique view.
• No direct interchange with Interstate 57.
• Six Flags Great America

Lingo

Portions of the Tri-State Tollway are referred to in somewhat archaic language during traffic reports and casual conversation. The following are the most common, from south to north:

• Thornton Quarry -- on I-80/294, the bridge over the aforementioned Thornton Quarry.
• Mile-Long Bridge -- on I-294, the bridge over the Illinois Sanitary and Ship Canal , the Des Plaines River , a large portion of the UPS transmodal facility, a few rail lines, and some Commonwealth Edison power lines.
• Bensenville Bridge -- on I-294, the bridge over the Metra Milwaukee District West line and Mannheim Road (U.S. 12/45).
• Grand Avenue Curve -- The curve immediately preceding the Bensenville Bridge.
• The Water Tower -- on I-294, a water tower by Willow Road.
• Edens Extension -- the portion of I-94 that branches off the Tri-State Tollway to become the Edens Expressway , but is still part of the Illinois Tollway system.