Community Identity Project:
USPS Mailing Addresses in Unincorporated Alameda County

What is a USPS "Preferred Last Line" and why does it matter?

A Preferred Last Line (or Place Name) is the "City, State" line in a mailing address. The United States Postal Service (USPS) assigns ZIP Codes and Place Names as a way to simplify mail delivery. USPS ZIP Codes often cross municipal boundaries, and the USPS Place Names associated with those ZIP Codes don't always match official community names. This can have a negative impact on community identity, public health data collection, and on residents' ability to access essential public services

image of map showing thatplacenames and zip cods do not align with urban unincorporated Alameda County communities

Current USPS Place Names and ZIP codes do not align with urban unincorporated Alameda County communities

In unincorporated Alameda County, USPS Place Names are not based on any official community or city boundary. Instead, the USPS has historically assigned Place Names in this area based on thephysical location of the post office that delivers mail to each ZIP Code. For example, a resident of the 94541 ZIP Code living in the unincorporated community of Cherryland or Hayward Acres has aUSPS Place Name of "Hayward" - an incorporated City name - because the Hayward Post Office delivers mail in that ZIP Code.

More than 20,000 parcels in urban unincorporated Alameda County are impacted by mismatched USPS Place Names. Incorrect Place Names are especially impactful in Ashland, Cherryland, Hayward Acres,and Fairview because the names of those communities are not officially recognized by the USPS. Even the unincorporated communities of San Lorenzo and Castro Valley, which have their own post officesand their own USPS Place Names, are impacted by USPS boundaries that are inconsistent with official community boundaries. The map on this page shows how USPS ZIP Codes and USPS Place Names overlapwith the official community boundaries in unincorporated Alameda County.

Not sure which unincorporated community you live in? Look it up using the County's interactive Community Locator map.

Project History and Overview

Supervisor Nate Miley, District 4, launched the Eden Area Livability Initiative (EALI) in 2004 with the goals of improving the quality of life and health of the residents of the urban unincorporated communities. EALI had 2 phases. During EALI Phase II (2012-2019), a "ZIP Code Realignment" project arose from the Governance Working Group to address the unintentional impacts of misaligned ZIP Codes and mismatched USPS Place Names on unincorporated community identity, data collection, and service delivery. Follow links below to view the EALI Governance working group's presentations on this topic:

Since 2022, at Supervisor Miley's request, the Community Development Agency (CDA) has held this work via the re-named "USPS Project," an ongoing effort focused on researching options with the USPS, gathering community input, and proposing solutions to the Alameda County Board of Supervisors and the USPS.

CDA staff connected with regional representatives from the USPS and presented the community with several options through an online survey and a series of community meetings leading up to a hearing with the Board of Supervisors in September, 2023.

Project Update September 2023: Board of Supervisors Supports Pursuing USPS Place Name Changes

At the September 21, 2023, planning meeting of the Alameda County Board of Supervisors, CDA staff presented an overview of the USPS Project, including community feedback, and outlined several solutions for the Board to consider.

The Board heard public comment before voting unanimously to approve a resolution "authorizing the Community Development Agency to submit a request to the United States Postal Service (USPS) tochange mailing address Place Names for unincorporated Ashland, Castro Valley, Cherryland, Fairview, Hayward Acres, and San Lorenzo to align with the Planning Area names and boundaries of thosecommunities, as defined in the Alameda County General Plan." The full staff memo andresolution are available here, and a description of the proposed change is below.

What is a USPS Place Name Change?

If approved by the USPS, residents would use their unincorporated community name as the official Place Name on their mail. "Official" means that USPS recognizes your unincorporated community name (Ashland, Cherryland, Hayward Acres, Fairview, San Lorenzo, or Castro Valley) as the default Place Name, reflected in address searches. "Hayward" and "San Leandro" would no longer be official Place Names in unincorporated or on, but residents could still use the old USPS Place Name as long as they use the correct ZIP Code and street address. ZIP codes would not change, and impacts to mail delivery would be minimal.

image showing address switch

Project Update March 2024: Gathering Address Data and Next Steps

Since the Board took action in September 2023, CDA staff have been working to acquire and analyze address data and prepare a formal request to the USPS. We will email an announcement to our USPS Project listserv when this request is submitted, and will keep the listserv informed about any progress made on the request.

If approved by USPS, the changes should take effect within 6 months of approval. Staff will then design an outreach campaign to inform community about the approved changes. Click here to subscribe to our listserv to receive updates as the project progresses.

Project Update April 2024: Supervisor Miley requests letters of support for Place Name Changes!

The County is preparing its request for Place Name changes and plans to submit its request to USPS this summer! You can help strengthen the County's application by writing a letter of support for this project. See this message from Supervisor Nate Miley with a sample letter to help you get started.

Please submit your letters of support by May 10, 2024, to or

Nate Miley, Supervisor, District 4
Attn: USPS Project Support Letter
20980 Redwood Road, Suite 250
Castro Valley, CA 94546

Staff Contact

Alison Abbors
Alameda County Community Development Agency Planning Department
Phone: (510) 670-5428
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