There's a great deal to be said for modeling railroads prior to 1900: the locos and cars are shorter and you can fit a great deal more into a given area; you don't have to worry about complicated stuff like signals and motor vehicles. While there haven't been a great deal of models available, that has changed in the last few years with the great products being offered by SMR trains. You can also find kits for pre-1900 freight cars from a few manufacturers. If you get a chance, check out Bernie Kempinski's work on his Civil War era layout at his blog http://usmrr.blogspot.com/ . There really is a great deal that can be done. Besides, pre-1900 brings out the best in O Scale... There is enough to get you going and more than enough that you have to do yourself.
I have attached a photo of SMR's lates loco release: a Pennsy D6a from about 1882. They also have a D6 and beautiful Pennsy passenger cars. There are 4 photos of cars I've build and, a photo of a car I built from a BTS kit. Check them out.
