The report issued Thursday says O'Hare International Airport will have congestion until at least 2013, and the FAA also says that Midway Airport won't be able to add more flights after 2020.
FAA spokesman Greg Martin says the report should be incentive for lawmakers to act.
Chicago Mayor Richard Daley and others have been pushing a $15 billion modernization plan for O'Hare. The plan hasn't yet received federal approval.
Others are pushing for a new, third airport in suburbs south of Chicago.