Traffic situation determination systems, methods, and programs acquire a current position of the vehicle based on a radio signal received from a GPS satellite and determine a first travel path of the vehicle based on the acquired position of the vehicle. The systems, methods, and programs determine whether a road on which the vehicle is traveling has a traffic jam. If the road on which the vehicle is traveling has a traffic jam, the systems, methods and programs transmit first information relating to the first travel path from the vehicle to an information center. The systems, methods, and programs receive second information relating to a second travel path of the vehicle, the second information being received from a mobile phone communication center and being based on a mobile phone signal received by the mobile phone communication center. The systems, methods, and programs determine a road corresponding to the first travel path as having a traffic jam and determine a road corresponding to the second travel path, and not corresponding to the first travel path, as having no traffic jam.