The Dan Ryan Expressway runs from the Circle Interchange with I-290 near downtown Chicago through the south side of the city. It is designated as both Interstate 90 and Interstate 94 north of 66th Street, a distance of 7.44 miles (11.97 km), and only Interstate 94 south of its connection with the Chicago Skyway near 66th Street, a distance of 4.03 miles (6.49 km). This is a total distance of 11.47 miles (18.5 km).
On an average day, between 71,000 and 307,100 vehicles use part of the Dan Ryan (2005 data). The Dan Ryan and its North Side extension, the Kennedy Expressway, are the busiest roads in Illinois. Utilizing an express-local system, the Dan Ryan has fourteen lanes of traffic, seven in each direction, with four of those express lanes and the other three providing access to exits. Despite its width, the Dan Ryan is prone to traffic jams. The Dan Ryan's express-local system is similar to that of Toronto's Highway 401.
As with the Kennedy Expressway, the posted directions on the Dan Ryan are different than the actual compass direction of the expressway, which causes confusion to many travelers. The Dan Ryan for its entire 12-mile (19 km) length runs north and south. However the Dan Ryan is just a very small part of Interstates 90 and 94, which are signed as east–west routes. Therefore, one who is traveling "west" on I-90/94 is actually driving north on the Dan Ryan; similarly, "east" is really south. Chicagoans typically refer to the directions of travel as "inbound" and "outbound" from downtown.