Residential delivery area · New Hampshire
ZIP Code 03837: Gilmanton Iron Works, NH
ZIP code 03837 uses the postal name Gilmanton Iron Works, New Hampshire and lies entirely in Belknap County (Census 2020 ZIP-county file). About 1,500 people live there (Census Bureau, ACS 2020-2024). Median household income is $119,712 (Census Bureau, ACS 2020-2024). Its land lies outside any incorporated or census-designated place.
- ACS2020-24
- Census2020
- FHFA2025
- ZBP2023
- IRS2022
- Town
- Gilmanton Iron Works · its only residential ZIP
- County
- Belknap County
- Micro area
- Laconia, NH
- House district
- NH-1 119th Congress
- State
- New Hampshire
- Time zone
- Eastern
- Land area
- 20.0 sq mi · 73 people per sq mi
Where is ZIP code 03837?
03837 centers on 43.422°, -71.336° and covers 20.0 square miles of land plus 0.7 of water. It borders 5 ZIP codes: 03237, 03225, 03810, 03218, 03809.
The map draws ZIP code areas only. For the streets inside 03837, open its center on OpenStreetMap.
Source: U.S. Census Bureau, 2020 ZCTA cartographic boundaries and the 2023 Gazetteer (2020 ZCTAs); ZIP-to-county shares, Census places and House districts (119th Congress) from the Census 2020 relationship files (shares of land); metro area from the OMB delineation (July 2023); town name and time zone from simplemaps US ZIP Codes (CC BY 4.0).
How does 03837 compare with the rest of Belknap County?
| Measure | 03837 | In Belknap County | In NH |
|---|---|---|---|
| People (ACS 2020-2024) | 1,451 | 12th of 14 | 172nd of 247 |
| Median household income | $120k | 1st of 9 | 39th of 158 |
| Median home value | $410k | 6th of 14 | 76th of 191 |
Its median household income is higher than in 90% of U.S. residential ZIP codes, and it is denser than 49% of all U.S. residential ZIP codes. ZIP codes at the ACS caps ($250,000 or more for household income, $2,000,000 or more for home value) share the top rank.
Source: U.S. Census Bureau, ACS 2020-2024 5-year estimates (B01003, B19013, B25077); ranks by PlainZIP over residential ZIP codes (ZCTAs).
How many people live in 03837?
The 2020 Census counted 1,471 people in 03837; the ACS, which samples households over 2020-2024, estimates 1,451. Between the 2010 and 2020 censuses its population fell 3.2% (its boundary stayed at least 90% the same).
- People, ACS 2020-2024
- 1,451±459 (90% margin)
- 2020 Census count
- 1,471−3.2% since 2010 (1,519)
- Households
- 602
- Median age
- 55.1
Source: U.S. Census Bureau, ACS 2020-2024 5-year estimates (B01003, B01002, B11001); 2020 Census (DHC P1); 2010 Census (SF1 P1).
Who lives in 03837?
Of the 1,451 people the ACS estimates in 03837, 18.9% are under 18 and 21.6% are 65 or older. The largest group by race and Hispanic origin is White (not Hispanic) (96.8%).
- Under 1818.9%
- 18 to 6459.5%
- 65 and older21.6%
- White, not Hispanic96.8%
- Black, not Hispanic1.8%
- Other or two or more1.4%
- Hispanic or Latino0.0%
- Asian, not Hispanic0.0%
Source: U.S. Census Bureau, ACS 2020-2024 5-year estimates (B01001 age by sex, B03002 Hispanic or Latino origin by race); shares of the estimated population, small ZIP codes carry wide margins.
What do households in 03837 earn?
Median household income is $119,712 (ACS 2020-2024), the highest of the 9 ranked ZIP codes in Belknap County. It rose from $80,462 in 2015-2019 (in 2024 dollars), a change larger than the surveys' margins of error.
- Median household income
- $119,712±$14,441
- Income per person
- $54,328
- Below the poverty line
- 1.5%
- Unemployed (of the labor force)
- 1.1%
- Adults 25+ with a bachelor's degree
- 41.1%
- Adjusted gross income per tax return, 2022
- $86,895740 returns; wages 72% of AGI (IRS)
Source: U.S. Census Bureau, ACS 2020-2024 and 2015-2019 5-year estimates (B19013, B19301, B17001, B23025, B15003; 2015-2019 dollars converted with the BLS CPI-U, 1.22699); IRS Statistics of Income, ZIP code data, tax year 2022 (adjusted gross income per return, filed under the address on the return).
What are homes worth in 03837?
FHFA's house price index for 03837, built from repeat sales and appraisals of the same homes, rose 106% from 2015 to 2025 and rose 67% from 2020 to 2025, and moved −14.7% in 2025.
- Median home value (owners' estimate)
- $409,600
- Median gross rent
- –
- Homes owned by their occupants
- 99.7%
- Housing units
- 956
Source: U.S. Census Bureau, ACS 2020-2024 5-year estimates (B25077, B25064, B25003, B25001); FHFA House Price Index, annual five-digit ZIP, updated 2026-03-31.
What businesses are in 03837?
24 business establishments had a location in this ZIP code in 2023, 2 more than in 2018; the most are in construction (ZIP Code Business Patterns).
- Construction7
- Professional, scientific, and technical services4
- Accommodation and food services4
- Other services (except public administration)4
Source: U.S. Census Bureau, ZIP Code Business Patterns 2023 and 2018 (establishments with paid employees, by the business's ZIP code).
Which ZIP codes are next to 03837?
| ZIP | Town | People | Household income | Distance |
|---|---|---|---|---|
| 03237 | Gilmanton | 2,575 | $111k | 2.7 mi |
| 03225 | Center Barnstead | 3,834 | $112k | 6.2 mi |
| 03810 | Alton Bay | 2,314 | $148k | 6.6 mi |
| 03218 | Barnstead | 1,160 | $113k | 6.7 mi |
| 03809 | Alton | 3,680 | $106k | 7.4 mi |
| 03249 | Gilford | 7,830 | $117k | 7.0 mi (near) |
| 03220 | Belmont | 7,393 | $68k | 8.2 mi (near) |
| 03307 | Loudon | 5,724 | $107k | 8.2 mi (near) |
Source: PlainZIP from the Census 2020 ZCTA boundaries (shared edges) and internal points; figures ACS 2020-2024.