If you have a related table of state abbreviations, you can omit every record where the value in the abbreviation field does not match.
If you put a return separated list of all Abbreviations into a single text field of a single record, it could also be used as that related table of state abbreviations.
If you have a value list of the abbreviations, you can set up a calculation field that returns a 1 if the value in the ST field is also in the value list. Then you can perform a find for all records with a 1 in this calculation field.
Thank for the quick reply, I'll try some of those ideas and report back. Database already has a maintained field (in a related file) that has a <rtn> separated list of ST abbrevs (USA and Canada).