Wouldn't that be something, never ending, and always updated info source on industries that use, or have used rail service. The big industries we all know about, it's pretty obvious, and we do our best to compress the various rail served segments of a huge industry.
The smaller and more obscure industries, you almost have to stumble apon while researching some thing else. Such as a place, right here in my small town, there was a glass recycler. He shipped out the crushed glass in open hoppers. Maybe 2 a week. Nothing big, by any means. When the huge trash collection companies offered recycling along with the weekly trash, either by garbage can or a dumpster, he lost a lot of his source. But, in a data base for such industries, you would be able to find his operation, the years it operated, and what rail cars it used, in and outbound.
Quite a fantasy I have going here, hey? that such a data base could excist? What a monumental research effert it would take to even begin!
I also think that the map programs we all use, Google Earth, Bing, etc., etc., all make a huge difference in reseaching a particular railroad, even your own model rail road, as you sorta have an idea of the area your modeling, and some hours in front of a screen will give you a good idea what industies there are, but, thats only good for today. Not for the past, such as the 30's, 40's, and 50's, which is the era that so many modelers do. Now you have to go deeper, into the past, to find what your looking for, and look for historical maps and charts.
I also learned that watching videos, in which Central Ink surfaced, is another great source, as long as you look for videos such as this one, that show daily operations.
To me the researching is a huge part of the fun. I love history. That's why when a thread shows up in here about a long gone and obscure railroad, I can't help but jump in, and check it out!
OK, I'm done. Now I'll post it and see how typos I need to fix!