ZIP Code 91743

91743 is one of California's ZIP codes, delivering to addresses in Guasti, San Bernardino County.

City: Guasti
County: San Bernardino County
State: California
Prefix: 917xx

Where this code sits

91743 is part of the 917xx range, the group of codes handled by one mail processing centre. It is the only ZIP code delivering to Guasti.

Area codes over the same ground

Postal and telephone geography are drawn separately, so these codes cover the area 91743 delivers to without sharing its boundary.

ZIP codes nearest 91743

The ZIP codes whose reference points sit closest to 91743.
ZIP code	Distance	Delivers to
ZIP code 91764	2.4 mi	Ontario, CA
ZIP code 91729	2.9 mi	Rancho Cucamonga, CA
ZIP code 91730	2.9 mi	Rancho Cucamonga, CA
ZIP code 91761	3.0 mi	Ontario, CA
ZIP code 91758	3.7 mi	Ontario, CA
ZIP code 91762	4.6 mi	Ontario, CA
ZIP code 91701	5.1 mi	Rancho Cucamonga, CA
ZIP code 91785	5.3 mi	Upland, 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 91743, plotted from its record coordinates.

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

Scope ZIP code 91743. 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.