Interstate 294 (I-294) is a tolled auxiliary Interstate Highway in the northeastern part of the U.S. state of Illinois. Forming the southern portion of the Tri-State Tollway in Illinois, I-294 runs from South Holland at I-80/I-94 and Illinois Route 394 (IL 394) to Northbrook at I-94. I-294 is long; are shared with I-80. It serves as a bypass around the city of Chicago. I-294 is also the longest auxiliary route of I-94, at longer than I-494 in Minneapolis–Saint Paul. In addition, the tollway is the longest auxiliary Interstate Highway in Illinois, and it intersects the most primary Interstate Highways at six. Route description I-294 begins at the interchange between I-94, I-80, and IL 394 in Lansing. I-94 splits off toward Chicago while I-80/I-294 heads west as an eight-lane tollway and crosses above a railroad track and Thorn Creek in Thornton. The highway crosses under the Chicago Southland Lincoln Oasis, Chicago Road, another railroad track, and State Street through residential areas. I-80/I-294 is between the Thornton Quarry on an elevated area before crossing the quarry on a bridge and passing under another railroad track. The highway then enters East Hazel Crest and has a cloverleaf interchange with IL 1 (Halsted Street) and widens to 10 lanes. Then, I-80/I-294 reenters the residential areas and center cross over Center Avenue, the Canadian National Railway Chicago Subdivision, the Metra electric line, and the Dixie Highway. After crossing under 171st Street, I-80 splits off and heads toward Des Moines, Iowa, and I-294 narrows to eight lanes in Hazel Crest. After the I-80 split, I-294 heads north and enters Markham. It crosses under 167th Street and goes through the 163rd Street toll plaza. I-294 has a cloverleaf interchange with US Route 6 (US 6; 159th Street) and turns northwest toward an incomplete interchange with I-57. I-294 then enters Posen and has a partial interchange with IL 83 (147th Street). I-294 turns west to cross the Metra Rock Island District and Kedzie Avenue. I-294 turns northwest, and enters Midlothian. It crosses over South Claire Boulevard, Pulaski Road, the Midlothian Turnpike, 135th Street, and the Calumet River. I-294 has an interchange with IL 50 and IL 83 (Cicero Avenue) with a northbound exit and southbound entrance via 127th Street in Alsip. It then passes by warehouses and crosses over Ridgeland Avenue, 115th Street, 111th Street, 107th Street, another Metra line, Southwest Highway, Stony Creek, all while entering Worth,