Union County
Tennessee · County seat: Maynardville · Active county or equivalent
FIPS code 47173 is Union County, Tennessee. With a population of 19,860 (2022 ACS estimate), it ranks #67 in Tennessee and #1877 nationally. Union County is part of the Knoxville, 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
47173
Population
19,860
2022 ACS · #1877 nationally
Density
88.8/mi²
people per sq mile
Land Area
224
sq miles
Urban/Rural
Metro — 250K–1M population
RUCC 2
How This FIPS Code Works
The 5-digit FIPS code 47173 is formed by combining the 2-digit state identifier 47 (Tennessee) with the 3-digit county identifier 173. Together they uniquely identify Union County in every US federal dataset. No two counties share the same 5-digit FIPS code.
Census ACS Data for FIPS 47173
From the 2022 ACS 5-year estimates — the same values you'd retrieve by querying the Census API with county FIPS 47173.
Median Household Income
$57,094
ACS B19013_001E
Poverty Rate
15.9%
ACS B17001 (below poverty level)
Median Age
42.6
ACS B01002_001E
Metropolitan Area
Adjacent Counties (5)
Counties that share a border with Union County. Useful for regional analysis — these are the geographies you'd typically include when studying labor markets, commuting zones, or environmental spillovers around FIPS 47173.
Federal Datasets Using Code 47173
FIPS code 47173 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 47173 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:173",
"in": "state:47",
"key": "YOUR_CENSUS_API_KEY",
}
r = requests.get(url, params=params)
data = r.json() # [[header...], [Union County, Tennessee, income, pop, ...]-- 5-digit combined FIPS (state + county)
SELECT * FROM your_table WHERE county_fips = '47173';
-- Some datasets store state and county separately
SELECT * FROM your_table
WHERE state_fips = '47'
AND county_fips = '173';
-- ⚠ Never cast to integer — leading zeros are lost:
-- county_fips = 47173 is WRONG for this countylibrary(tidycensus)
get_acs(
geography = "county",
variables = c(income = "B19013_001E", pop = "B01003_001E"),
state = "47",
county = "173",
year = 2022
)ZIP Codes in Union 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 Union County. Why FIPS ≠ ZIP →
| ZIP Code | % in county |
|---|---|
| 37866 | 100.0% |
| 37807 | 99.3% |
| 37779 | 95.8% |
| 37705 | 30.7% |
| 37848 | 25.3% |
| 37870 | 10.2% |
| 37721 | 9.9% |
| 37888 | 9.2% |
| 37825 | 5.2% |
| 37754 | 4.4% |
| 37938 | 0.6% |