There is a new feature called data validation that can be enabled at the table level. I can't seem to get the help system to search in the last couple of days, but you make a formula to calculate an error message. If the formula is blank result then the record will save, else it will block the save with an error.
Note that if you enable this you would need to deal with the old records, or maybe have the formula only abort the save where [date created] is after June 27, 2019.
Or else make users fix the state even though they may not have been the ones to enter it wrong.
Post back if you need a list of states.