Steam Locomotives Travels

[Overmod]

SPer

Why would a railroad assign a steamer to only one terminal-to-terminal route instead of the entire system.

Often, in the old days, because that is as far as they could go without requiring service.  

In many cases there were weight or other restrictions that kept locomotives on particular routes.  The C&NW E-4b Hudsons come to mind, as do the N&W As not being able to operate where train-control had been installed.  The last NYC steam locomotives to operate were, as I recall, in service on track too light for even the smallest comparable first-generation diesel road switchers.

Even later, locomotives were assigned where shop forces were equipped or more familiar with them.  Even with diesels this could be observed; for example this was a major factor in supporting Baldwins or FM-equipped engines in commuter service in the East and in California respectively.

ATSF liked to use its 84"-drivered Hudsons from Chicago west across Kansas, but those locomotives were ill-suited to some of the Western grades.  Although they could famously 'run through' without servicing, there was no particular need for them to do so: they were swapped out for (more capable, as it turned out!) 4-8-4s which continued the run through to California.

In some cases the 'first best use' of locomotives was on runs between two fairly specific points.  The Niagaras putting up the high mileage numbers by 1947 were doing so in a specific service, running a very specific turn (from Harmon, north of New York, to Chicago) and they were by far most effectively used there.

[SPer]

When a railroad buys a steam locomotive from a bulder,such as ALCO,Baldwin,and Lima, they assigned them to one division only like,say the Chicago and North Western 4-8-4s running on the Chicago-Omaha main line or Wabash 4-8-4s running between Decatur ,IL and Montepelier,Ohio and not the whole system.Why would a railroad assign a steamer to only one terminal-to-terminal route instead of the entire system.