U.S. postal lookup

U.S. ZIP Codes Database 2026

Search by ZIP code, city, county, or state and find clear postal details with maps, time zones, and area code data.

42,735 verified records
All states and U.S. territories
Maps and coordinates
County directory

Belknap County ZIP Codes

Browse all ZIP Codes, cities, and associated area codes registered in Belknap County.

County State ZIP Code City Area Codes
Belknap County NH 03256 New Hampton 603
Belknap County NH 03269 Sanbornton 603
Belknap County NH 03289 Winnisquam 603
Belknap County NH 03298 Tilton 603
Belknap County NH 03299 Tilton 603
Belknap County NH 03809 Alton 603
Belknap County NH 03810 Alton Bay 603
Belknap County NH 03837 Gilmanton Iron Works 603
Page 2 of 2

Geographic Map of Belknap County

Postal context

About U.S. ZIP Codes

ZIP codes are a United States Postal Service system introduced in 1963 to make mail routing more accurate and efficient. The standard format uses five digits, while ZIP+4 adds four more digits for a more precise delivery segment.

ZIP codes cover the United States, its territories, military mail routes, and other USPS delivery points. This directory organizes that data for practical lookup by ZIP code, city, county, and state.