The economic model is highy abstracted and you may not be helped too much from reading books about the period. If you're just interested in learning history, then there are many, but none that I know of will help you with the game,
per se. If you're wanting help about how to build your economy, there are two strategy guides posted on this forum, one for the North, one for the South, that are quite helpful as a place to start.
If you are interested in actual history, to be perfectly honest, I'd pick up one of the college texts about the Civil War and Reconstruction. You'll can find them at Barnes, Amazon, Borders, etc. The best ones were written before 1985 or so. Sorry to say that most of them are spendy. There are good ones to be had that are more recent, but there are also some that have been politicised a little too much for my tastes. Also be careful that they don't deal with things you may not have an interest in. I've seen some that deal with music, art, archtecture, etc. of the period, exclusively.
There's also an excellent used bookstore in Portland, Oregon, named Powell's Books that WILL have what you want. Whenever I'm in Portland I spend a day there. They are on the internet, and have good bargains on almost everything. Their search engine is pretty good, too.
http://www.powells.com/psection/History.html
Once you've gotten a little satisfaction from the first book, whatever you select, use the references in that book to locate more in-depth volumes, if you want more. A good textbook should give you all you want, though, unless you're really into historical economies.
Other folks may have something on their shelves that they like; most of mine deal with the military/social aspects of the war. That's because many years ago, I came to the conclusion that the North had, the South didn't, and realized that that was all I needed to know. (A little exaggeration, but not much.) I HAVE read several excellent volumes about the economic imbalance of the two sides over the years, but don't recall what they were and certainly didn't purchase them -- my bookshelves are packed to the brim without them.
Can anybody else help with a specific volume?