US Postal Service Zone Improvement Plan (ZIP) Codes are used throughout the United States to improve mail delivery. There are 479 unique 5-digit ZIP Codes in Oregon all starting with 97. All ZIP Codes are assigned and managed exclusively by the US Postal Service. There are three main categories of ZIP Codes - 1) Standard, 2) PO Box Only, 3) Unique for large commercial and government customers.Each ZIP Code is assigned a preferred city name by the US Postal Service. NOTE - these city names may not correspond with the city limits or other jurisdiction boundaries of incorporated cities. There are other acceptable city names listed that may be used for mailing addresses for some ZIP Codes. There are also other city names to avoid using for mailing addresses. To verify the preferred, acceptable, or city names to avoid enter the ZIP Code in this tool from the US Postal Service - https://tools.usps.com/zip-code-lookup.htm?citybyzipcodeThis is not a product of the US Postal Service. It was compiled by checking all numbers from 97000 - 97999 with the ZIP Code Lookup tool.Most Standard and some PO Box Only ZIP Codes may also be listed as Census ZIP Code Tabulation Areas (ZTCA). NOTE - The ZTCA is only an approximation of a ZIP Code area based on the predominate ZIP Code of all housing units in each Census block. ZIP Codes actually follow lines of travel along letter carrier routes and are not polygons as shown by the ZTCA.