Williamson County
Tennessee · County seat: Franklin · Active county or equivalent
FIPS code 47187 is Williamson County, Tennessee. With a population of 248,897 (2022 ACS estimate), it ranks #6 in Tennessee and #276 nationally. Williamson County is part of the Nashville-Davidson--Murfreesboro--Franklin, TN. The state FIPS code for Tennessee is 47. This code is used in Census Bureau, BLS, EPA, HUD, and USDA federal datasets to identify this county.
County FIPS
47187
Population
248,897
2022 ACS · #276 nationally
Density
427.2/mi²
people per sq mile
Land Area
583
sq miles
Urban/Rural
Metro — 1M+ population
RUCC 1
How This FIPS Code Works
The 5-digit FIPS code 47187 is formed by combining the 2-digit state identifier 47 (Tennessee) with the 3-digit county identifier 187. Together they uniquely identify Williamson County in every US federal dataset. No two counties share the same 5-digit FIPS code.
Census ACS Data for FIPS 47187
From the 2022 ACS 5-year estimates — the same values you'd retrieve by querying the Census API with county FIPS 47187.
Median Household Income
$125,943
ACS B19013_001E
Poverty Rate
4.2%
ACS B17001 (below poverty level)
Median Age
40.0
ACS B01002_001E
Metropolitan Area
Adjacent Counties (7)
Counties that share a border with Williamson County. Useful for regional analysis — these are the geographies you'd typically include when studying labor markets, commuting zones, or environmental spillovers around FIPS 47187.
Federal Datasets Using Code 47187
FIPS code 47187 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 47187 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:187",
"in": "state:47",
"key": "YOUR_CENSUS_API_KEY",
}
r = requests.get(url, params=params)
data = r.json() # [[header...], [Williamson County, Tennessee, income, pop, ...]-- 5-digit combined FIPS (state + county)
SELECT * FROM your_table WHERE county_fips = '47187';
-- Some datasets store state and county separately
SELECT * FROM your_table
WHERE state_fips = '47'
AND county_fips = '187';
-- ⚠ Never cast to integer — leading zeros are lost:
-- county_fips = 47187 is WRONG for this countylibrary(tidycensus)
get_acs(
geography = "county",
variables = c(income = "B19013_001E", pop = "B01003_001E"),
state = "47",
county = "187",
year = 2022
)ZIP Codes in Williamson 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 Williamson County. Why FIPS ≠ ZIP →
| ZIP Code | % in county |
|---|---|
| 37069 | 100.0% |
| 37179 | 100.0% |
| 37067 | 100.0% |
| 37064 | 99.2% |
| 37062 | 93.2% |
| 37046 | 92.0% |
| 37135 | 88.6% |
| 37027 | 86.4% |
| 37014 | 69.4% |
| 38476 | 42.3% |
| 37174 | 23.7% |
| 37060 | 12.7% |
| 37221 | 8.1% |
| 37025 | 3.2% |
| 38401 | 2.1% |
| 37215 | 1.7% |