Steam loco operation

[nachoman]

My "1960" comment further explained:

Up to 1960, you could find examples of limited steam use in many places in the USA/Canada. Whether that be as helpers for a few weeks, diesel shortage, or shortlines/industrial railroads. You could conceivably run steam on any pre 1960 layout and offer reasoning, and the modeling police are unlikely to arrest you . Any railroad running steam (other than tourists or excursions) after 1960 is generally well documented by railfans. 1960 is a good "rule of thumb" year for when steam went from being "limited service" to "very rare". As pointed out already, the Colorado and Southern and D&RGW were using steam in Colorado. Those examples are well documented. I know some industrial railroads were using steam in the early 1960s (the lead mines in Picher OK come to mind). The Magma Arizona Railroad (short mining operation) operated steam until 1968, and the Crab Orchard and Egyptian Railway was a mostly tourist operation but used steam to haul freight until the mid 1980s.

My point is, if you want to be plausible, you can perhaps create a reasoning that a local industry kept a steam switcher going until about 1962 or 1963. But, it would be pretty far-fetched to have even a freelanced railroad running mainline steam after 1960.