Address Management System (AMS) is the United States Postal Service master database of deliverable addresses.
Address-checking tools using AMS provide address standardization, as well as city/state and ZIP Code lookup features.
[1] Business mailers use the USPS Address Management System:-[e correct ZIP Codes.
City/state lookup services use AMS to provide the city and state corresponding to any given ZIP Code.
[2] AMS is also a general term describing a technological solution for managing street addressing.