They were built to haul the road's 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 MotorsElectro-Motive Division for new diesel locomotives. The displaced E-4s instead worked other trains until they were withdrawn from service in 1953 and scrapped.
The nine E-4s 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 they were different in almost every detail of design.
CNW Class E4-6-2 – Some converted to "ES" class with similar shrouding to the E-4. The ES engines succeeded Class D locomotives on the Minnesota 400.
CNW Class E-2 4-6-2 – Twelve locomotives, four of which were converted to "E-2-a" class and were the original locomotives for the Twin Cities to Chicago 400 before being replaced by EMD E3 diesel units. The remaining eight were converted to "E-2-b" locomotives.