Foster County
North Dakota · County seat: Carrington · Active county or equivalent
FIPS code 38031 is Foster County, North Dakota. With a population of 3,388 (2022 ACS estimate), it ranks #32 in North Dakota and #3002 nationally. The state FIPS code for North Dakota is 38. This code is used in Census Bureau, BLS, EPA, HUD, and USDA federal datasets to identify this county.
County FIPS
38031
Population
3,388
2022 ACS · #3002 nationally
Density
5.3/mi²
people per sq mile
Land Area
635
sq miles
Urban/Rural
Nonmetro — completely rural
RUCC 9
How This FIPS Code Works
The 5-digit FIPS code 38031 is formed by combining the 2-digit state identifier 38 (North Dakota) with the 3-digit county identifier 031. Together they uniquely identify Foster County in every US federal dataset. No two counties share the same 5-digit FIPS code.
Census ACS Data for FIPS 38031
From the 2022 ACS 5-year estimates — the same values you'd retrieve by querying the Census API with county FIPS 38031.
Median Household Income
$78,426
ACS B19013_001E
Poverty Rate
8.4%
ACS B17001 (below poverty level)
Median Age
45.1
ACS B01002_001E
Adjacent Counties (4)
Counties that share a border with Foster County. Useful for regional analysis — these are the geographies you'd typically include when studying labor markets, commuting zones, or environmental spillovers around FIPS 38031.
Federal Datasets Using Code 38031
FIPS code 38031 appears as the county identifier in the following federal datasets. Analysts joining data across these sources use this code as the common geographic key.
Using FIPS Code 38031 in Code
Common patterns for querying federal datasets by this county's FIPS code. The leading zeros are significant — always treat FIPS codes as strings, not integers.
import requests
url = "https://api.census.gov/data/2022/acs/acs5"
params = {
"get": "NAME,B19013_001E,B01003_001E",
"for": "county:031",
"in": "state:38",
"key": "YOUR_CENSUS_API_KEY",
}
r = requests.get(url, params=params)
data = r.json() # [[header...], [Foster County, North Dakota, income, pop, ...]-- 5-digit combined FIPS (state + county)
SELECT * FROM your_table WHERE county_fips = '38031';
-- Some datasets store state and county separately
SELECT * FROM your_table
WHERE state_fips = '38'
AND county_fips = '031';
-- ⚠ Never cast to integer — leading zeros are lost:
-- county_fips = 38031 is WRONG for this countylibrary(tidycensus)
get_acs(
geography = "county",
variables = c(income = "B19013_001E", pop = "B01003_001E"),
state = "38",
county = "031",
year = 2022
)ZIP Codes in Foster County
ZIP codes do not align perfectly with county boundaries — a single ZIP code can span multiple counties, and a county can contain parts of many ZIP codes. The ratios below (from the Census 2020 ZCTA relationship file) show the land area share of each ZCTA that falls within Foster County. Why FIPS ≠ ZIP →
| ZIP Code | % in county |
|---|---|
| 58443 | 100.0% |
| 58421 | 82.9% |
| 58445 | 65.0% |
| 58455 | 41.4% |
| 58464 | 35.5% |
| 58484 | 26.6% |
| 58356 | 6.0% |
| 58426 | 4.4% |