The easiest solution is to make it both a drop down pick list and option to enter it by direct typing. Solves future issues with "this code is not included" or "insurance added this code for our specific region". Where you store the pick list won't matter with this solution. By the way, I found a *bug* to enter it anyways but it does not get generated (put into the CMS-1500). Just a simple copy a text like "GA" and paste and it will get it past the inability to enter it directly... but as I said, it won't be generated into the CMS-1500 bill.
Don't understand why loading it from the database would be "SLOOOOOOWW". Load at time of App launch so it persists during the life of the App since it's not something you modify more than once in a blue moon. It should be loaded from a local DB file on the computer so there is no need to load it across the network.