I've tried just asking for zip instead of city and state but then watch people as they type their city and state into the address line. Also theoretically peopl

I've tried just asking for zip instead of city and state but then watch people as they type their city and state into the address line. Also theoretically people may mistype their zip and you'll have no way to validate it against what they typed in the city/state. The best is the auto-fill from some list of all valid addresses I'd say.