ZIP Code 91310 — Castaic, California
📍 ZIP code 91310 is in Castaic, Los Angeles County, California.
ZIP code 91310 is a PO Box ZIP code assigned by the U.S. Postal Service in Castaic, Los Angeles County, California. It serves post office boxes at a Castaic post office rather than street addresses, which is why the Census Bureau reports no resident population, income or housing figures for it. Mail addressed to 91310 is handled in the Pacific Time Zone and the local area code is 818. The demographic profile of the surrounding community is on the standard delivery ZIP pages for Castaic listed below.
Why there are no demographics for 91310
The Census Bureau publishes demographics for ZIP Code Tabulation Areas (ZCTAs), which are built from populated census blocks. A PO Box ZIP like 91310 has no delivery territory of its own, so there is no ZCTA and no population, income, housing or education estimate to report. This is normal: Los Angeles County and the rest of California have hundreds of PO Box and unique ZIPs of this kind.
For the community around Castaic, use the delivery ZIPs that do carry Census data:
How ZIPs and ZCTAs differ is explained on the methodology page.
Nearby Zip Codes
Cities & Places Served
ZIP code 91310 primarily serves Castaic in Los Angeles County, California.