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The locomotive on the front of this post card is working for the Northern Pacific Railroad in the 1950s. It is a "Consolidation" model of locomotive. I have taken excerpts from this website https://www.american-rails.com/consolidation.html and from this article on the website:

2-8-0 "Consolidation" Locomotives

The article was written (and last revised September 20, 2023) by Adam Burns The first 2-8-0 is said to have appeared on the Pennsylvania Railroad around the end of the Civil War. The history of the Consolidation's origins is interesting; the first prototype actually constructed is said to have been built by the Lehigh & Mahanoy Railroad around 1865, which modified a standard 0-8-0 switcher by adding a front axle to the locomotive. The original designs were not very successful as they were mounted with a rigid front truck assembly instead of one that could freely move to more easily negotiate curves. However, a year later it was perfected by Matthias Baldwin's Baldwin Locomotive Works, which improved the 2-8-0 by making the lead truck/axle self-centering via its mount from the driving wheels. This not only greatly improved stability but also since the lead axle freely swiveled it vastly enhanced the locomotive's ability to negotiate curves. The first Consolidation purchased from a manufacturer was built by Baldwin and delivered to the Lehigh Valley in 1866 for use on the road's stiff grades of its Mount Carmel Branch in Pennsylvania. The 2-8-0 design was a significant technological leap from the 4-4-0 as its heavier frame and larger boiler greatly increased tractive effort and horsepower. In particular, mountain railroads found the design very useful for both of these reasons. The Consolidation, with its two extra driving axles and front pilot truck could not only pull trains that were twice as heavy but also run at speeds fast enough to be used in any type of passenger service. By the 1880s Consolidations had become universally accepted as main line power. The post card was published by the mysterious Railcards.com