The nine E-4's were almost identical in specification and purpose to the Milwaukee Road's six class F7 locomotives, and they were built by the same builder at the same time, yet their streamlined designs were different.

The E-4's were built to haul the Chicago and North Western's (C&NW) famous "400" express passenger trains, but before they were even delivered, the railroad's management decided that streamlined steam was the wrong direction and instead placed orders with General Motors Electro-Motive Division for new diesel locomotives.

The displaced E-4s instead pulled secondary passenger trains, until they were withdrawn from service between 1953 and 1956, and scrapping commenced on the fleet.

4008 and 4009) were kept in Escanaba, Michigan to thaw frozen ore with heat from their boilers.

4008 and 4009 were replaced by a new infrared process, and since both E-4's had been welded to the rails, C&NW crews had to scrap them on site.