FIPS code 51109 is Louisa County, Virginia. With a population of 38,106 (2022 ACS estimate), it ranks #47 in Virginia and #1239 nationally. The state FIPS code for Virginia is 51. This code is used in Census Bureau, BLS, EPA, HUD, and USDA federal datasets to identify this county.
County FIPS
51109
Population
38,106
2022 ACS · #1239 nationally
Density
76.8/mi²
people per sq mile
Land Area
496
sq miles
Urban/Rural
Nonmetro — rural, adjacent to metro
RUCC 8
How This FIPS Code Works
The 5-digit FIPS code 51109 is formed by combining the 2-digit state identifier 51 (Virginia) with the 3-digit county identifier 109. Together they uniquely identify Louisa County in every US federal dataset. No two counties share the same 5-digit FIPS code.
Census ACS Data for FIPS 51109
From the 2022 ACS 5-year estimates — the same values you'd retrieve by querying the Census API with county FIPS 51109.
Median Household Income
$76,594
ACS B19013_001E
Poverty Rate
10.9%
ACS B17001 (below poverty level)
Median Age
45.0
ACS B01002_001E
Adjacent Counties (6)
Counties that share a border with Louisa County. Useful for regional analysis — these are the geographies you'd typically include when studying labor markets, commuting zones, or environmental spillovers around FIPS 51109.
Federal Datasets Using Code 51109
FIPS code 51109 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 51109 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:109",
"in": "state:51",
"key": "YOUR_CENSUS_API_KEY",
}
r = requests.get(url, params=params)
data = r.json() # [[header...], [Louisa County, Virginia, income, pop, ...]-- 5-digit combined FIPS (state + county)
SELECT * FROM your_table WHERE county_fips = '51109';
-- Some datasets store state and county separately
SELECT * FROM your_table
WHERE state_fips = '51'
AND county_fips = '109';
-- ⚠ Never cast to integer — leading zeros are lost:
-- county_fips = 51109 is WRONG for this countylibrary(tidycensus)
get_acs(
geography = "county",
variables = c(income = "B19013_001E", pop = "B01003_001E"),
state = "51",
county = "109",
year = 2022
)ZIP Codes in Louisa 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 Louisa County. Why FIPS ≠ ZIP →
| ZIP Code | % in county |
|---|---|
| 23093 | 94.9% |
| 23117 | 89.9% |
| 23024 | 81.9% |
| 22942 | 51.9% |
| 23065 | 23.9% |
| 23102 | 18.2% |
| 22974 | 14.8% |
| 23084 | 7.1% |
| 22947 | 6.6% |
| 23192 | 4.1% |
| 23015 | 1.0% |
| 23153 | 0.3% |