Boxcabs were either diesel-electric or electric locomotives. Most North American boxcabs were built a few years before and after 1930, the most prominent builders being GE and Alco.
Design
Boxcabs did not have heavily styled ends or a superstructure consisting of multiple structures, although the prototype diesel/oil-electric, GE no. 8835, had one end prominently rounded – attributed to its trolley (tram) car ancestry – and the second and following 100-ton ALCO boxcabs had semi-cylindrical ends.