The Chicago, Milwaukee, St. Paul and Pacific Railroad (Milwaukee Road) classes EP-1 and EF-1 comprised 42 boxcab electric locomotives built by the American Locomotive Company (Alco) in 1915. Electrical components were from General Electric. The locomotives were composed of two half-units semi-permanently coupled back-to-back, and numbered as one unit with 'A' and 'B' suffixes. As built, 30 locomotives were assigned to freight service, classified as EF-1 and numbered 10200–10229. The remaining twelve locomotives were assigned to passenger service as class EP-1, numbered 10100–10111, with higher-speed passenger gearing. The design was highly successful, replacing a much larger number of steam locomotives, cutting costs and improving schedules. General Electric self-proclaimed this electric locomotive to be the “King of the Rails” in a silent promotional film from 1915.