ZIP Code 91003

91003 is one of California's ZIP codes, delivering to addresses in Altadena, Los Angeles County.

City: Altadena
County: Los Angeles County
State: California
Prefix: 910xx

Where this code sits

91003 is part of the 910xx range, the group of codes handled by one mail processing centre. Altadena is served by 2 ZIP codes in total.

Area codes over the same ground

Postal and telephone geography are drawn separately, so these codes cover the area 91003 delivers to without sharing its boundary.

ZIP codes nearest 91003

The ZIP codes whose reference points sit closest to 91003.
ZIP code	Distance	Delivers to
ZIP code 91001	0.5 mi	Altadena, CA
ZIP code 91104	1.5 mi	Pasadena, CA
ZIP code 91103	2.1 mi	Pasadena, CA
ZIP code 91199	3.0 mi	Pasadena, CA
ZIP code 91102	3.0 mi	Pasadena, CA
ZIP code 91109	3.0 mi	Pasadena, CA
ZIP code 91110	3.0 mi	Pasadena, CA
ZIP code 91114	3.0 mi	Pasadena, 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 91003, plotted from its record coordinates.

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

Scope ZIP code 91003. 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.