This article is from the Paper Money Collecting FAQ, by Bruce Giese firstname.lastname@example.org with numerous contributions by others.
The two biggest paper money shows are in Memphis (every June)
and St. Louis (every October/November). There is also a big show
in Maastrict every year (April?). In addition, there is a
section in each copy of Bank Note Reporter which details paper
money shows in the USA and around the world. Most states have
a few every year.