ZIP code · Newmarket · New Hampshire · United States
ZIP code 03857 — Newmarket
ZIP code 03857 serves Newmarket, New Hampshire.
- Postal code
- 03857Single source Value from one source, not cross-checked.
- City
- Newmarket
- County
- Rockingham
- State
- New Hampshire
- Country
- United States
- Coordinates
- 43.0726, -70.9553 — precision precise (locality)
View on OpenStreetMap - Population
- 9,431 (ZCTA, ACS 5-year)
- Median household income
- $94,345
- Median age
- 39.3
- Time zone
- America/New_York (UTC−5 / UTC−4 DST)
- Area code
- 603Telephone area codes serving this ZIP (NANPA central-office assignments). A ZIP and an area code are different boundaries; at a border both codes may apply.
Nearby localities
About this page
US ZIP codes have five digits. They are postal routing areas, not administrative boundaries: a ZIP can span more than one city or county, and the city shown is the primary USPS name for that code.
GeoNames · U.S. Census Bureau (ACS). Data generated on 2026-08-21. Methodology · Report an error on this page