Illinois state highway system Illinois Tollway system

Interstate 90 (I-90) in the U.S. state of Illinois runs roughly northwest-to-southeast through the northern part of the state, from the Wisconsin state line near Rockford to the Indiana state line at Chicago. I-90 traverses 108 miles (174 km) through a variety of settings, from farmland west of the Fox River Valley through the medium-density suburban west of O'Hare International Airport, through downtown Chicago, and through the heart of the industrial southeast side of Chicago before entering Indiana.

I-90 comprises several named highways. The Interstate runs along the Jane Addams Memorial Tollway from Rockford to O'Hare Airport, the Kennedy Expressway runs from O'Hare to the Chicago Loop, the Dan Ryan Expressway from the Loop to the Chicago Skyway, and the Skyway to the Indiana state line. The Jane Addams and Chicago Skyway are toll roads maintained by the Illinois State Toll Highway Authority and Skyway Concession Company, respectively. The remainder of the highway is maintained by the Illinois Department of Transportation.

The Chicago Skyway, also known as Chicago Skyway Toll Bridge System, is a 7.8-mile-long (12.6 km) toll road in Chicago carrying I-90 from the Indiana Toll Road to the Dan Ryan Expressway on Chicago's South Side. The main feature of the Skyway is a 1⁄2-mile-long (0.80 km) steel truss bridge, known as the "High Bridge". The toll bridge spans the Calumet River and Calumet Harbor, a major harbor for industrial ships. The main span is 650 feet (200 m) long, provides for 125 feet (38 m) of vertical clearance, and is the highest road in Chicago.

The Jane Addams Tollway was built in the late 1950s and early 1960s as the Northwest Tollway. It was renamed in 2007 after Addams, the Nobel laureate and founder of the Settlement House movement in the United States. Between 2001 and 2004, authorities spent $250 million to rebuild much of the Chicago Skyway.

Interstate 90 enters from Wisconsin with I-39. At the U.S. Route 51 (US 51) exit, I-39/90 becomes the Jane Addams Memorial Tollway. The two Interstates run south to Rockford, where I-39 continues as a freeway south to La Salle–Peru. I-90 continues southeast along the tollway through the Chicago area. In Schaumburg, I-90 meets the western end of I-290, the only loop from I-90 in Illinois.

I-90 passes O'Hare International Airport, where I-190, the only spur of I-90 in Illinois, branches west to the airport terminals. I-90 continues southeast as the Kennedy Expressway and is later joined with eastbound I-94; westbound I-94 runs on the Edens Expressway. I-90 and I-94 then pass through the city, intersecting the eastern end of I-290 just west of the Chicago Loop. South of I-290, the highway is given the name of the Dan Ryan Expressway.

In Chicago's South Side, I-90 splits off from I-94 and becomes the Chicago Skyway, again becoming a toll road. I-90 then runs directly southeast to the Indiana state line, and becomes the Indiana Toll Road at the state line.

Often confusing to non-residents is the direction system for I-90/94, in which signs that say "I-90/94 West" go north/northwest and signs that say "I-90/94 East" go south/southeast. This naming system is due to the overall direction of the expressway. I-90/94 West goes north, splits into I-94 and I-90, continues north to Wisconsin, and then goes west, I-90 going to Seattle. I-90/94 East goes south, splitting into two pieces, and then turns northeast, I-90 ending in Boston.

Historically, the Chicago Skyway was signed as, and was widely considered to be part of, I-90 from the mid-1960s forward (after I-90 in this area had been swapped with I-94). However, around 1999, the city of Chicago realized they had never received official approval to designate the Skyway as I-90. The city subsequently replaced most of the "I-90" signage with "TO I-90/I-94" signage. However, the Illinois DOT has always and continues to report the Skyway as part of the Interstate system, and the Federal Highway Administration apparently still considers the Chicago Skyway an official part of I-90.

The Skyway's official name, referring to it as a "toll bridge" rather than a "toll road", is the result of a legal quirk. At the time of its construction, the city charter of Chicago did not provide the authority to construct a toll road. However, the city could build toll bridges, and it was found that there was no limit to the length of the approaches to the bridge. Therefore, the Skyway is technically a toll bridge with a six-mile-long approach. This also is part of the reason that there are no exits available until after one has crossed the bridge and paid the toll.

From O'Hare to Huntley, the region around the Jane Addams Tollway is sometimes referred to as the "Golden Corridor", due to the proximity of commercial and business activity located along the corridor in Northwest Suburban Chicago. Several Fortune 500 companies, large malls, hotels, entertainment and exhibition facilities, restaurants, and retailers are located along the corridor.

Along the Jane Addams Tollway, there are four mainline toll barriers in each direction – two split plazas and two full plazas. The barriers are located around the O'Hare International Airport area (River Road eastbound and Devon Avenue westbound), in Elgin, near Marengo (Eastbound), in Belvidere (Westbound), and in South Beloit. I-39 travelers exiting or entering at Rockford paid at the Cherry Valley toll plaza, but that toll plaza has been decommissioned southbound in 2003 and northbound in 2004 due to traffic congestion. In February 2006, the Marengo westbound and the Belvidere eastbound toll plazas were removed. Two two-toll plazas near O'Hare and the one in Elgin each charge cash tolls of 80 cents (as of January 1, 2005) and I-Pass tolls of 40 cents for a 2-axle passenger vehicle. The South Beloit toll plaza near the Illinois and Wisconsin state line is $1.00 (50 cents for I-Pass users). Eastbound traffic does not pay a toll at Belvidere because of the removal of the eastbound Belvidere plaza, but pays $1.60 at Marengo (I-Pass users pay $0.80). On the other hand, westbound traffic pays no toll at Marengo but pays $1.60 at Belvidere (I-PASS users pay $0.80). This change was done to accommodate open road tolling construction. Originally, a ticket system was used to compute tolls on the segment between Beloit and Elgin with each driver receiving a Hollerith card upon entering and paying upon exiting, but it was replaced with a cash barrier system in the late 1970s. It was the only portion of the Illinois Tollways to use a ticket system. Remnants of the old system can still be seen at several interchanges on the system including at the State Street exit near Rockford.

The current rate for passenger cars and other two axle vehicles on the Chicago Skyway is $4.00; vehicles with more axles pay higher rates. A discount is given during the overnight hours for vehicles with three or more axles.

There are two oases on the Jane Addams Tollway—one at Belvidere and one in Des Plaines near O'Hare. Both are over-highway oases. There is also a welcome center south of Beloit, Wisconsin, that is located on the IDOT portion of the highway between the border with Wisconsin and Illinois tollway control. At the Chicago Skyway's toll plaza, there is a McDonald's at highway grade in the road's median.

The 76-mile (122 km) Northwest Tollway portion of I-90 opened on August 20, 1958. Prior to the opening, the first vehicle to officially travel the new roadway was a covered wagon navigated by local resident John Madsen who took 5 days to make the journey.

On September 7, 2007, the Northwest Tollway was renamed the Jane Addams Memorial Tollway after Jane Addams, the Nobel Peace Prize winner and founder of the Settlement House movement in the United States.

The Chicago Skyway was originally known as the Calumet Skyway. It cost $101 million (1958, $791 million in 2011) to construct and took about 34 months to build. Nearly eight miles of elevated roadway, the Chicago Skyway was originally built as a shortcut from State Street, a major north-south street on Chicago's South Side that serves the Loop, to the steel mills on the Southeast to the Indiana state line where the Indiana Toll Road begins. Later, when the Dan Ryan Expressway opened, the Chicago Skyway was extended west to connect to it. There are only two eastbound exits east of the toll barrier, whereas there are four westbound exits west of the toll barrier. The Chicago Skyway opened to traffic on April 16, 1958.

In the 1960s, the newly constructed Dan Ryan Expressway and the neighboring Calumet Expressway, Kingery Expressway and Borman Expressway provided free alternatives to the tollway, and the Skyway became much less used. As a result, from the 1970s through the early 1990s, the Skyway was unable to repay revenue bonds used in its construction.

Traffic volumes have rebounded in recent years, (to 47,700 vehicles per day) partially because of the construction of casinos in Northwest Indiana, along with re-construction of the Dan Ryan, Kingery and Borman Expressways. The city of Chicago claims a record number of motorists used the Skyway in 2002.

In 2003 and 2004, the city of Chicago initiated a $250 million project to rehabilitate and widen the Skyway. The project involved extensive work on the cantilever span and its approaches that included replacing the bridge's structural steel, rebuilding the piers that support the structure, and reconstructing the bridge deck. Because the city of Chicago required the Skyway to remain open during construction, engineers had to construct temporary bridge piers that would bear the load of the bridge and its traffic while new piers were built. Once ready, the city of Chicago partnered with Enerpac company to complete a complex lift system. The bridge was lifted up onto the temporary piers using Enerpac 600 ton hydraulic jacks, the old piers were removed, and new ones were built. Crews also devised innovative methods for replacing the bridge's structural steel, replacing steel members one at a time. This process involved installing hydraulic chords around the component to be replaced. The bridge load was then transferred to the hydraulic chord, the steel member was removed and a new steel member was then installed.

Recently, major construction on both the Kingery and Borman expressways has increased traffic on the Skyway, as well as the presence of riverboat casinos in Hammond and East Chicago, Indiana. In June 2005, the Skyway became compatible with electronic toll collection, with users now able to pay tolls using I-PASS, I-Zoom, or E-ZPass transponders. There is no discount for using a transponder.

The city of Chicago's Department of Streets and Sanitation formerly maintained the Chicago Skyway Toll Bridge System. A transaction that gave the city of Chicago a $1.83 billion dollar cash infusion leased the Skyway to the Skyway Concession Company (SCC), a joint-venture between the Australian Macquarie Infrastructure Group and Spanish Cintra Concesiones de Infraestructuras de Transporte S.A., which assumed operations on the Skyway on a 99–year operating lease. SCC will be responsible for all operating and maintenance costs of the Skyway but has the right to all toll and concession revenue. The Triple-A bond insurer Financial Security Assurance Inc. (FSA) has guaranteed $1.4 billion of senior bonds to provide long-term funding for the privately operated Chicago Skyway. On June 30, 2006, this same joint-venture assumed responsibility for operating and maintaining the adjacent Indiana East–West Toll Road for $3.8 billion. The agreement between SCC and the city of Chicago marked the first time an existing toll road was moved from public to private operation in the United States.

Exits along the Jane Addams Memorial Tollway and Chicago Skyway are unnumbered.