ZIP Codes of Foster County, ND

Population & People
Population & People
Total Population
3,536
Household Income
Household Income
Median Income
$72,696
Housing
Housing
Total Housing Units
1,855
Business & Economy
Business & Economy
Total Businesses
135
Employment
Employment
Employment Rate
65.70%
Education
Education
Bachelor's Degree+
28.02%
Source: U.S. Census ACS 2024 5-Year Estimates · rolled up across the 4 ZIPs in this county.
Data Last Updated: June 1, 2026
ZIP Codes:4 ZIP Codes (4 Standard, 0 PO Box, 0 Unique) [See All]
Area Code:701
Timezone:Central (GMT -06:00)
Local Time:2:13:01 PM
Population:3,536 [See All]
FIPS:38031
Land Area:739 sq mi
Water Area:18 sq mi
Coordinates:47.5197, -98.7797
Quick Link:
https://www.zip-codes.com/county/nd-foster.asp
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North Dakota's #28 most populous county
3,536 residents across 4 ZIPs — #28 of 64 North Dakota counties.

Standout ZIPs in this County


Most Populous
Carrington · 2,969 people
84.0% of county total
Highest Income
Carrington · $89,097 median
1.2× county average
Largest Land Area
Carrington · 411.6 sq mi
Spans the most ground
Fastest Growth
Carrington · 4.9% (10-yr)
2,830 → 2,969 residents
Most Educated
Carrington · 30.3% bachelor's+
667 of 2,202 adults 25+

Things worth knowing about Foster County


3,536 residents live across 4 ZIPs covering 739 sq mi, served by 4 distinct USPS-recognized cities.

Population moved from 3,472 to 3,536 from 2014 to 2024 — a +1.8% change. 2 ZIPs gained residents, 2 lost.

The county's wealthiest ZIP 58421 (Carrington, $89,097 median) and poorest ZIP 58464 (Mchenry, $55,938) are 25.5 miles apart — a 1.6× income gap across local geography.

Median home values vary 1.6× across this county — from $109,400 in 58445 (Grace City) to $171,200 in 58421 (Carrington).

Density varies across the county — from 1 people/sq mi in 58443 (Glenfield) to 7 in 58421 (Carrington).

Educational attainment ranges from 11.8% bachelor's+ in 58443 (Glenfield) to 30.3% in 58421 (Carrington) — the breadth of educational profiles across the area.

Within North Dakota, this is the #28 most populous of 64 counties and ranks #39 for median household income .

Weighted by population, the typical household earns about $85,204 across the county — reflecting what a typical resident sees, not a simple ZIP average.

28.0% of adults age 25+ hold a bachelor's degree or higher (736 of 2,627 reporting).

4 Standard delivery, 0 PO Box only, 0 single-entity Unique ZIPs serve this county.

Stories about Foster County


Big & sparse

A frontier county — vast land area with only a few residents per square mile. Daily life looks very different here than in the country's denser counties.

Total area
739
square miles
Avg density
4.8
people per sq mi
Population
3,536
across 4 ZIPs
Carrington
411.6 sq mi
2,969 residents
Mchenry
158.3 sq mi
270 residents
Glenfield
111.2 sq mi
152 residents

Single-ZIP anchor

One ZIP holds the majority of this county's population — a sign of a county built around a single city or town.

Carrington

All ZIP Codes in Foster County


ZIPCityTypePopulationMedian IncomeArea (sq mi)10-yr Growth
58421CarringtonStandard2,969$89,097411.64.9%
58464MchenryStandard270$55,938158.3-17.9%
58443GlenfieldStandard152$73,500111.2-29.3%
58445Grace CityStandard145$72,25057.848.0%

Adjacent & Nearby Counties