Hi @twj1522,
Out of the box, the State/Region property is a single-line text property which leads to your data inconsistencies.
Unfortunately, once it’s in use (referenced in lists, reports, workflows, has values for contacts), you cannot easily change the type. You would first have to clear it before you can change its type (export values, remove all references, change type, re-import values, re-establish references).
Alternatively, create a new State property that is a dropdown (pick State from this dropdown in the screenshot).
You could then export your State/Region values, clean them up, re-import them into your new property and voilà, clean property.
Best regards!