FIPS code 51510 is Alexandria city, Virginia. With a population of 157,594 (2022 ACS estimate), it ranks #13 in Virginia and #424 nationally. Alexandria city is part of the Washington-Arlington-Alexandria, DC-VA-MD-WV. 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
51510
Population
157,594
2022 ACS · #424 nationally
Density
10,485.3/mi²
people per sq mile
Land Area
15
sq miles
Urban/Rural
Metro — 1M+ population
RUCC 1
How This FIPS Code Works
The 5-digit FIPS code 51510 is formed by combining the 2-digit state identifier 51 (Virginia) with the 3-digit county identifier 510. Together they uniquely identify Alexandria city in every US federal dataset. No two counties share the same 5-digit FIPS code.
Census ACS Data for FIPS 51510
From the 2022 ACS 5-year estimates — the same values you'd retrieve by querying the Census API with county FIPS 51510.
Median Household Income
$113,179
ACS B19013_001E
Poverty Rate
8.8%
ACS B17001 (below poverty level)
Median Age
37.4
ACS B01002_001E
Metropolitan Area
Adjacent Counties (4)
Counties that share a border with Alexandria city. Useful for regional analysis — these are the geographies you'd typically include when studying labor markets, commuting zones, or environmental spillovers around FIPS 51510.
Federal Datasets Using Code 51510
FIPS code 51510 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 51510 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:510",
"in": "state:51",
"key": "YOUR_CENSUS_API_KEY",
}
r = requests.get(url, params=params)
data = r.json() # [[header...], [Alexandria city, Virginia, income, pop, ...]-- 5-digit combined FIPS (state + county)
SELECT * FROM your_table WHERE county_fips = '51510';
-- Some datasets store state and county separately
SELECT * FROM your_table
WHERE state_fips = '51'
AND county_fips = '510';
-- ⚠ Never cast to integer — leading zeros are lost:
-- county_fips = 51510 is WRONG for this countylibrary(tidycensus)
get_acs(
geography = "county",
variables = c(income = "B19013_001E", pop = "B01003_001E"),
state = "51",
county = "510",
year = 2022
)ZIP Codes in Alexandria city
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 Alexandria city. Why FIPS ≠ ZIP →
| ZIP Code | % in county |
|---|---|
| 22314 | 100.0% |
| 22301 | 100.0% |
| 22305 | 100.0% |
| 22304 | 96.6% |
| 22302 | 95.6% |
| 22311 | 75.8% |
| 22312 | 8.4% |
| 22206 | 2.9% |