53033 FipsDecoder
16065 County FIPS Code

Madison County

Idaho · County seat: Rexburg · Active county or equivalent

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FIPS code 16065 is Madison County, Idaho. With a population of 52,487 (2022 ACS estimate), it ranks #7 in Idaho and #968 nationally. Madison County is part of the Rexburg, ID. The state FIPS code for Idaho is 16. This code is used in Census Bureau, BLS, EPA, HUD, and USDA federal datasets to identify this county.

County FIPS

16065

State FIPS

16

ID

Population

52,487

2022 ACS · #968 nationally

Density

111.9/mi²

people per sq mile

Land Area

469

sq miles

Urban/Rural

Nonmetro — urban 20K+, adjacent to metro

RUCC 4

How This FIPS Code Works

16 065
16 = State FIPS (Idaho)
065 = County FIPS

The 5-digit FIPS code 16065 is formed by combining the 2-digit state identifier 16 (Idaho) with the 3-digit county identifier 065. Together they uniquely identify Madison County in every US federal dataset. No two counties share the same 5-digit FIPS code.

Census ACS Data for FIPS 16065

From the 2022 ACS 5-year estimates — the same values you'd retrieve by querying the Census API with county FIPS 16065.

Median Household Income

$53,025

ACS B19013_001E

Poverty Rate

30.1%

ACS B17001 (below poverty level)

Median Age

21.6

ACS B01002_001E

Metropolitan Area

Adjacent Counties (4)

Counties that share a border with Madison County. Useful for regional analysis — these are the geographies you'd typically include when studying labor markets, commuting zones, or environmental spillovers around FIPS 16065.

Federal Datasets Using Code 16065

FIPS code 16065 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 16065 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.

Census ACS API — Python 16065
import requests

url = "https://api.census.gov/data/2022/acs/acs5"
params = {
    "get":  "NAME,B19013_001E,B01003_001E",
    "for":  "county:065",
    "in":   "state:16",
    "key":  "YOUR_CENSUS_API_KEY",
}
r = requests.get(url, params=params)
data = r.json()  # [[header...], [Madison County, Idaho, income, pop, ...]
SQL — filtering by county FIPS 16065
-- 5-digit combined FIPS (state + county)
SELECT * FROM your_table WHERE county_fips = '16065';

-- Some datasets store state and county separately
SELECT * FROM your_table
WHERE state_fips = '16'
  AND county_fips = '065';

-- ⚠ Never cast to integer — leading zeros are lost:
-- county_fips = 16065 is WRONG for this county
R — tidycensus 16065
library(tidycensus)

get_acs(
  geography = "county",
  variables = c(income = "B19013_001E", pop = "B01003_001E"),
  state     = "16",
  county    = "065",
  year      = 2022
)
Zero-padding reminder: FIPS codes must always be stored and compared as zero-padded strings. 16 (not 16) and 065 (not 65) — losing the leading zeros is one of the most common data-join bugs in federal datasets. Full guide →

ZIP Codes in Madison 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 Madison County. Why FIPS ≠ ZIP →

ZIP Code % in county
83460 100.0%
83448 98.1%
83440 96.1%
83436 76.0%
83451 66.7%
83434 27.7%
83443 1.2%
83445 0.3%

Other Counties in Idaho