We had a 2 hour ground delay on SK946 ORD-ARN around 4:30. We taxied out to the edge of the apron to the taxiway and sat there for 2 hours. The delay was so long that the pilot shutdown the engines and the FA's served snacks. When we finally started back up and got onto the taxiway the backup on the active taxiway to the runway was about 10 planes deep. Why is Chicago so bad and other airports like DTW not so bad? Is the climate really that much different???