Custer County
Montana · County seat: Miles City · Active county or equivalent
FIPS code 30017 is Custer County, Montana. With a population of 11,957 (2022 ACS estimate), it ranks #17 in Montana and #2351 nationally. The state FIPS code for Montana is 30. This code is used in Census Bureau, BLS, EPA, HUD, and USDA federal datasets to identify this county.
County FIPS
30017
Population
11,957
2022 ACS · #2351 nationally
Density
3.2/mi²
people per sq mile
Land Area
3,783
sq miles
Urban/Rural
Nonmetro — urban 2.5K–19.9K, not adjacent to metro
RUCC 7
How This FIPS Code Works
The 5-digit FIPS code 30017 is formed by combining the 2-digit state identifier 30 (Montana) with the 3-digit county identifier 017. Together they uniquely identify Custer County in every US federal dataset. No two counties share the same 5-digit FIPS code.
Census ACS Data for FIPS 30017
From the 2022 ACS 5-year estimates — the same values you'd retrieve by querying the Census API with county FIPS 30017.
Median Household Income
$61,114
ACS B19013_001E
Poverty Rate
11.1%
ACS B17001 (below poverty level)
Median Age
42.8
ACS B01002_001E
Adjacent Counties (6)
Counties that share a border with Custer County. Useful for regional analysis — these are the geographies you'd typically include when studying labor markets, commuting zones, or environmental spillovers around FIPS 30017.
Federal Datasets Using Code 30017
FIPS code 30017 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 30017 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:017",
"in": "state:30",
"key": "YOUR_CENSUS_API_KEY",
}
r = requests.get(url, params=params)
data = r.json() # [[header...], [Custer County, Montana, income, pop, ...]-- 5-digit combined FIPS (state + county)
SELECT * FROM your_table WHERE county_fips = '30017';
-- Some datasets store state and county separately
SELECT * FROM your_table
WHERE state_fips = '30'
AND county_fips = '017';
-- ⚠ Never cast to integer — leading zeros are lost:
-- county_fips = 30017 is WRONG for this countylibrary(tidycensus)
get_acs(
geography = "county",
variables = c(income = "B19013_001E", pop = "B01003_001E"),
state = "30",
county = "017",
year = 2022
)ZIP Codes in Custer 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 Custer County. Why FIPS ≠ ZIP →
| ZIP Code | % in county |
|---|---|
| 59338 | 100.0% |
| 59301 | 81.3% |
| 59345 | 68.0% |
| 59336 | 65.5% |
| 59351 | 39.5% |
| 59347 | 7.6% |
| 59349 | 1.3% |