"Flight delays have beset the U.S. national airspace system. In 2007, more than one-quarter of all flights either arrived late or were canceled across the system, according to the Department of Transportation (DOT). DOT and its operating agency, the Federal Aviation Administration (FAA), are making substantial investments in transforming to a new air traffic control system--the Next Generation Air Transportation System (NextGen)--a system that is expected to reduce delays over the next decade. This requested report explains the extent to which (1) flight delays in the U.S. national airspace system have changed since 2007 and the contributing factors to these changes, and (2) actions by DOT and FAA are expected to reduce delays in the next 2 to 3 years. We analyzed DOT and FAA data for FAA's Operational Evolution Partnership (OEP) airports because they are in major metropolitan areas, serving over 70 percent of passengers in the system. We reviewed agency documents and interviewed DOT, FAA, airport, and airline officials and aviation industry experts."--Highlights.