The Northwest Tollway in Illinois is a 79 mile (127 km) segment of Interstate 90 from Interstate 190 in far northwest Chicago to Illinois State Route 75, one mile south of the Wisconsin state line. For 16 miles (26 km), Interstate 90 is multiplexed with Interstate 39 and U.S. Highway 51. It consists of four lanes west of Elgin (2 each direction), and six east of Elgin (3 each direction).

East of Interstate 190, Interstate 90 merges into the Kennedy Expressway.

Toll Barriers

There are four mainline toll barriers, each having cash tolls of 80 cents (as of January 1, 2005) and I-PASS tolls of 40 cents for a 2-axle passenger vehicle. The barriers are located around the O'Hare Airport area, in Elgin, in Belvidere, and in South Beloit. Interstate 39 travelers exiting/entering at Rockford used to have to pay at the Spring Valley toll plaza, but that toll plaza has been demolished due to traffic concerns.

The Northwest Tollway is maintained by the Illinois State Toll Highway Authority.

Oases

There are two oases on the Northwest Tollway -- one at Belvidere, and one by O'Hare. Both are the over-highway oases that have become fixtures of the Illinois Tollway system. There is also a welcome center south of Beloit, WI.