From 1863 until 1935 the United States issued National Banknotes. These banknotes gave the Federal Government a way to get more currency in circulation, and thus borrow money to fund federal spending. There were 14,348 National Banks most of whom issued currency and there is always a special joy of collecting a "home-town" note!
This reference (just released Oct. 2011), designed for the specialist and dealer, offers the most complete data to be found anywhere for small-size currency, organized and listed by specific series, including accurate population figures for each. The book also contains detailed tutorial information. Most up-to-date census for all U.S. small-size currency.