The AEM-7 is a twin-cab B-B electric locomotive that is used in the United States on the Northeast Corridor between Washington DC and Boston and the Keystone Corridor between Philadelphia and Harrisburg in Pennsylvania. They were built by Electro-Motive Division from 1978 to 1988. There are two versions of the AEM-7 as of 1999: the original AEM-7DC which has DC propulsion equipment and the newer, modified AEM-7AC which uses AC propulsion equipment.