One thing I just recalled is that if you maintain a small exceptions lookup table (i.e. the ones that span state boundaries), you can use ZIP Codes as a way to uniquely look up a county name.
For example, health care plans in the US are county-specific with regard to premiums, co-pays, etc. (based on demographics). Allowing someone to type in their ZIP Code to get started can be a better user experience than having them pick their county.
Yeah it makes it easier. And I’m appreciative of the idea of making address entry easier for users but if they have to disambiguate did you actually make it easier?
I think Zillow does it best. You just type your address in a box and it looks up the normalized full address.