A C-17 sits on the tarmac at Chicago's Midway Airport prior to departure on Runway 4R. It's apparently part of the 437th Airlift Wing based at Joint Base Charleston, S.C. Presumably, it was in Chicago in support of the NATO Summit that was taking place.
Aircraft 08-8190:
The C-17 measures 174 feet long (53 meters) with a wingspan of 169 feet, 10 inches (51.75 meters). The aircraft is powered by four, fully reversible, Federal Aviation Administration-certified F117-PW-100 engines (the military designation for the commercial Pratt & Whitney PW2040), currently used on the Boeing 757. Each engine is rated at 40,440 pounds of thrust. The thrust reversers direct the flow of air upward and forward to avoid ingestion of dust and debris. Maximum use has been made of commercial off-the-shelf equipment, including Air Force-standardized avionics.
www.af.mil/information/factsheets/factsheet.asp?fsID=86 