The Milwaukee Road emerged from its second bankruptcy after World War II, so it must have felt rich enough to publish this booklet showing many of its historic and then-current locomotives. The booklet, which I scanned from the Spokane Public Library Northwest Collection, shows twelve steam locomotives that date from before 1920, six more modern steamers, four electrics, and a dozen Diesels.
Milwaukee was an eclectic buyer, with Diesels by Alco, Baldwin, Fairbanks Morse, General Electric, and General Motors, all of which (at least those shown in the booklet) were built in 1940 or later. By 1950, when this booklet was published, most of the post-1920 steam locomotives were probably still in use as were the pre-1920 electrics. (One series of electric locomotives, the “Little Joes,” were purchased by the Milwaukee in 1950.) The steam locomotives soon disappeared, but the electrics survived to the 1970s.