While there are several large limestone quarries within a half-hour drive from my home, as much of the Niagara Escarpment is limestone.
I don’t have a quarry on my layout, but my railroad moves a lot of limestone in open hoppers, all of it from “elsewhere”.
Likewise, there’s lots of coal moving in open hoppers, too, and many of them are from the same “elsewhere” as the coal mines, usually somewhere south of the Canadian border…that also offers a good excuse for running a lot of hoppers from American railroads.
I have a lumber yard on my layout, but the lumber comes from either northern Ontario or from British Columbia. The lumber yard simply sells to the nearby locals, usually loaded on a company truck or picked-up in small amounts by nearby customers.
I do run flatcars, gondolas and boxcars loaded with lumber, but most of it is just passing through.
I was originally going to have a steel mill, too, but a single blast furnace, with its ancillary structures would take up nine square feet of layout space, and there’d be no more room for a stripper building, or rolling mills, coke ovens, along with all the other necessities needed for steelmaking - I spent over 40 years in a steel plant, and models of those buildings would overwhelm even a large layout.
I do have a number of reasonably large factories producing things, and they get materials usually by rail, and then ship out finished goods either by rail or by truck, depending, of course, on the products they offer.
I don’t, however, have much room to allow things like hundred-car-trains , even though I used to run 70 or 80 car trains, simply to determine how many locomotives would be needed to move such trains up various grades.
Nowadays, 20 or 30 cars are enough to make a reasonable-looking tr