ZIP Code 91023

91023 is one of California's ZIP codes, delivering to addresses in Mount Wilson, Los Angeles County.

City: Mount Wilson
County: Los Angeles County
State: California
Prefix: 910xx

Where this code sits

91023 is part of the 910xx range, the group of codes handled by one mail processing centre. It is the only ZIP code delivering to Mount Wilson.

Area codes over the same ground

Postal and telephone geography are drawn separately, so these codes cover the area 91023 delivers to without sharing its boundary.

626 Area code 626

ZIP codes nearest 91023

The ZIP codes whose reference points sit closest to 91023.
ZIP code	Distance	Delivers to
ZIP code 91024	4.3 mi	Sierra Madre, CA
ZIP code 91003	4.5 mi	Altadena, CA
ZIP code 91025	4.5 mi	Sierra Madre, CA
ZIP code 91001	4.8 mi	Altadena, CA
ZIP code 91104	5.3 mi	Pasadena, CA
ZIP code 91107	5.4 mi	Pasadena, CA
ZIP code 91066	6.2 mi	Arcadia, CA
ZIP code 91077	6.2 mi	Arcadia, CA

Straight-line distance between place reference points, not driving distance. Where a place has no Census Gazetteer point, its postal centroid is used instead.

Each point is the reference point for 91023, plotted from its record coordinates.

Reference points and footprint
Not an official NANPA boundary
Not a USPS delivery area

Scope ZIP code 91023. Source GeoNames US postal codes (2026-07 postal dump) and Census 2024 county Gazetteer (2024 Gazetteer). Updated 15 July 2026. A ZIP code is a set of delivery routes, not an area; the point shown is a record coordinate, not a centre.