Chicago O'Hare International Airport is pictured in this file photo. [Chicago O'Hare airport]

The Chicago Department of Aviation on Thursday announced a bid opportunity to fill 112 new concessions locations at Terminals 1 and 3 at O'Hare International Airport, in what the city called “one of the largest concessions bid opportunities in the history of U.S. airports.” The bid opportunity is part of the airport’s ongoing modernization effort.