Chuck Sartor posted:2-8-4 were the first modern super power locomotives. NKP and Erie are two examples of roads that used them for fast freight, instead of freight drags. Maybe they had more 'giddy-up' than pull. Most western roads seems to like 4-8-2's. Then on to 4-8-4's.
Plus, the UP needed much more HP for freight, and went with the Challenger type of 4-6-6-4s, totally 105 such locomotives. Conversely, the SP simply kept expanding their cab forward class, plus 4-8-2s, 4-10-2 three cylinders, and most improved 2-10-2s. The GN and NP used heavy 2-8-2s and simple articulated locomotives, respectively.
The AT&SF preferred non-articulated power such as their various classes of 4-8-4s and huge 2-10-4s.
