Why would you want your users to have to type all the characters of a
state's name, only to watch while your application wipes out all of their
typing and replaces it with an abbreviation?  I'm guessing you have some
irate users!

Another approach would be to create a simple table that holds both state
name and state abbreviation.  Then, in your form, you could use a combobox
that displays the state name and lets the user pick the one they want, while
your form stores the (hidden) first column that contains the abbreviations.

Your users see full state names, but the system stores the abbreviations.

Good luck!

Regards

Jeff Boyce
Microsoft Office/Access MVP