In the 1930s, the Chicago & North Western, the Milwaukee Road and the Burlington Route competed on the line between Chicago and Minneapolis. The C&NW called these services “The 400 Train” since the target was to cover the 400 miles in 400 minutes, what makes an average speed of 60 mph or 97 km/h. While the Burlington Route chose to serve this line with a streamlined diesel train, the other two used streamlined 4-6-4 steam locomotives which were both built by ALCO-Schenectady and looked very similar with their Art Deco styling.

The nine class E-4 locomotives built for the C&NW were delivered in March and April 1938, some months earlier than the Milwaukee Road's F7. Both had drivers of 84 inches and a boiler pressure of 300 psi. The boiler of the E-4 was characterized by the fact that it had only eight flues instead of the 60 of the F7, but still a larger superheater area. This made a smaller tube heating area, but combined with the larger firebox and superheater the total heating area of both was roughly equal. The E-4 had Baker valve gear instead of the Walschaerts valve gear of the F7, while the cylinders of the E-4 had a larger diameter at a smaller stroke.

The locomotives were painted green with gold stripes. When they were still in production, it was decided to use diesel power for the 400 train. So they were actually used on services between Chicago and Omaha. They were converted to oil firing in 1946 and 1947 with tenders that held 6,000 gallons of oil.