Jefferson County
Montana · County seat: Boulder · Active county or equivalent
FIPS code 30043 is Jefferson County, Montana. With a population of 12,273 (2022 ACS estimate), it ranks #16 in Montana and #2326 nationally. Jefferson County is part of the Helena, MT. 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
30043
Population
12,273
2022 ACS · #2326 nationally
Density
7.4/mi²
people per sq mile
Land Area
1,656
sq miles
Urban/Rural
Metro — under 250K population
RUCC 3
How This FIPS Code Works
The 5-digit FIPS code 30043 is formed by combining the 2-digit state identifier 30 (Montana) with the 3-digit county identifier 043. Together they uniquely identify Jefferson County in every US federal dataset. No two counties share the same 5-digit FIPS code.
Census ACS Data for FIPS 30043
From the 2022 ACS 5-year estimates — the same values you'd retrieve by querying the Census API with county FIPS 30043.
Median Household Income
$73,875
ACS B19013_001E
Poverty Rate
5.1%
ACS B17001 (below poverty level)
Median Age
47.4
ACS B01002_001E
Metropolitan Area
Adjacent Counties (7)
Counties that share a border with Jefferson County. Useful for regional analysis — these are the geographies you'd typically include when studying labor markets, commuting zones, or environmental spillovers around FIPS 30043.
Federal Datasets Using Code 30043
FIPS code 30043 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 30043 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:043",
"in": "state:30",
"key": "YOUR_CENSUS_API_KEY",
}
r = requests.get(url, params=params)
data = r.json() # [[header...], [Jefferson County, Montana, income, pop, ...]-- 5-digit combined FIPS (state + county)
SELECT * FROM your_table WHERE county_fips = '30043';
-- Some datasets store state and county separately
SELECT * FROM your_table
WHERE state_fips = '30'
AND county_fips = '043';
-- ⚠ Never cast to integer — leading zeros are lost:
-- county_fips = 30043 is WRONG for this countylibrary(tidycensus)
get_acs(
geography = "county",
variables = c(income = "B19013_001E", pop = "B01003_001E"),
state = "30",
county = "043",
year = 2022
)ZIP Codes in Jefferson 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 Jefferson County. Why FIPS ≠ ZIP →
| ZIP Code | % in county |
|---|---|
| 59631 | 100.0% |
| 59632 | 100.0% |
| 59634 | 100.0% |
| 59638 | 100.0% |
| 59721 | 61.6% |
| 59759 | 61.2% |
| 59701 | 46.8% |
| 59635 | 36.2% |
| 59752 | 19.6% |