Essex County
Massachusetts · County seat: Salem · Independent city (not a county)
FIPS code 25009 is Essex County, Massachusetts. With a population of 806,103 (2022 ACS estimate), it ranks #3 in Massachusetts and #77 nationally. Essex County is part of the Boston-Cambridge-Newton, MA-NH. The state FIPS code for Massachusetts is 25. This code is used in Census Bureau, BLS, EPA, HUD, and USDA federal datasets to identify this county.
County FIPS
25009
Population
806,103
2022 ACS · #77 nationally
Density
1,636.6/mi²
people per sq mile
Land Area
493
sq miles
Urban/Rural
Metro — 1M+ population
RUCC 1
How This FIPS Code Works
The 5-digit FIPS code 25009 is formed by combining the 2-digit state identifier 25 (Massachusetts) with the 3-digit county identifier 009. Together they uniquely identify Essex County in every US federal dataset. No two counties share the same 5-digit FIPS code.
Census ACS Data for FIPS 25009
From the 2022 ACS 5-year estimates — the same values you'd retrieve by querying the Census API with county FIPS 25009.
Median Household Income
$94,378
ACS B19013_001E
Poverty Rate
9.7%
ACS B17001 (below poverty level)
Median Age
40.9
ACS B01002_001E
Metropolitan Area
Adjacent Counties (4)
Counties that share a border with Essex County. Useful for regional analysis — these are the geographies you'd typically include when studying labor markets, commuting zones, or environmental spillovers around FIPS 25009.
Federal Datasets Using Code 25009
FIPS code 25009 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 25009 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:009",
"in": "state:25",
"key": "YOUR_CENSUS_API_KEY",
}
r = requests.get(url, params=params)
data = r.json() # [[header...], [Essex County, Massachusetts, income, pop, ...]
-- 5-digit combined FIPS (state + county)
SELECT * FROM your_table WHERE county_fips = '25009';
-- Some datasets store state and county separately
SELECT * FROM your_table
WHERE state_fips = '25'
AND county_fips = '009';
-- ⚠ Never cast to integer — leading zeros are lost:
-- county_fips = 25009 is WRONG for this county
library(tidycensus)
get_acs(
geography = "county",
variables = c(income = "B19013_001E", pop = "B01003_001E"),
state = "25",
county = "009",
year = 2022
)
ZIP Codes in Essex 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 Essex County. Why FIPS ≠ ZIP →
| ZIP Code | % in county |
|---|---|
| 01985 | 100.0% |
| 01984 | 100.0% |
| 01810 | 100.0% |
| 01830 | 100.0% |
| 01832 | 100.0% |
| 01833 | 100.0% |
| 01834 | 100.0% |
| 01835 | 100.0% |
| 01840 | 100.0% |
| 01841 | 100.0% |
| 01843 | 100.0% |
| 01844 | 100.0% |
| 01845 | 100.0% |
| 01860 | 100.0% |
| 01901 | 100.0% |
| 01902 | 100.0% |
| 01904 | 100.0% |
| 01905 | 100.0% |
| 01906 | 100.0% |
| 01907 | 100.0% |
| 01908 | 100.0% |
| 01913 | 100.0% |
| 01915 | 100.0% |
| 01921 | 100.0% |
| 01922 | 100.0% |
| 01923 | 100.0% |
| 01929 | 100.0% |
| 01930 | 100.0% |
| 01937 | 100.0% |
| 01938 | 100.0% |
Showing top 30 of 46 ZIP codes by residential address share.