Adding to the good advice from above:
There is a lot of information about that era. But it is not available in a continuing magazine form. You'll have to prospect for it, pardner, jes like in the Ole West. Whoopie tie yie, etc.
There's some additional info sources.
One is a book by E. P. Alexander called "Iron Horses". It features 100 two-page "studies" of American locomotives from 1829-1900. No. 82 on is for 1890. But keep in mind that most locomotives working in 1890 were built prior. So, it's a pretty interesting summary of both the common and unusual in steam power in the US.
Another STUNNINGLY good book is John H. White, Jr.'s "The American Railroad Freight Car". Over 600 pages on the subject PRIOR to the "coming of steel". If you read it, you will know a LOT about the subject.
There are also, on occasion, books about your time period of interest that are railroad specific. On my desk is Schrenk and Frey's "The Northern Pacific Railroad: Engines of Growth, 1887-1905". 250 pages of pretty specific information about NP locomotives of your era of interest.
The US, being large-ish even then, had quite a variety of railroads and locales. You might have a specific local interest. Perhaps not now, but it can creep up on you.
There is a huge amount of prototype information (railroad, sort-of-railroad, somewhat-near-the-railroad, etc.) about the time period. Photography was well established. Books were actually written and read in those days. And some of it was even true.
I agree that modeling that era is not stunningly popular. Them's the breaks, as we say here. In motive power, there's a little available in plastic (as mentioned earlier). I recommend checking out the brass locomotives. I believe there's a much broader selection there. And I also think the prices will be lower than the ever-popular giants of steam. For freight rolling stock, I think you should plan on building your own from Evergreen styrene. Generally, the construction will be VERY simple. Tank and hopper cars will likely be different. Cast resin kits will likely become familiar to you. Westerfield is around. Sunshine Models used to be, but you might find some of theirs. They generally do/did "early-ish" freight cars. Many of which will be "too-late-ish" for you. But I suspect you will find something(s) of use from those people.
As noted earlier, the various historical societies are a source. So are the Yahoo Groups (and Facebook, I suppose). You will undoubtedly want to join this group:
I strongly recommend to join that Yahoo group. I'll bet they will have some VERY good advice on the matter.