[AccessD] question on normalization

quick question:
 
I have a program that will be populated with a 'regional' group of
people--this meaning that everyone's address will be within this county.
So I am thinking that I can speed up entry, by using a drop-down for zip
codes and filling the town name from that. My question is, would it be
proper to have a separate table for town and another for zip code, even
though zip code would be a single field table? The town table would have
three tables, with one being a link to the Zip Code table, and the Zip
Code table would have a single field--"Zip".
 
Thanks
 
John W Clark