53033 FipsDecoder
Independent city — not a county. Essex County has its own 5-digit FIPS code and appears as a county equivalent in federal datasets. It is administratively separate from any surrounding county.
25009 County FIPS Code

Essex County

Massachusetts · County seat: Salem · Independent city (not a county)

View on CensusDepth ↗

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

State FIPS

25

MA

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

25 009
25 = State FIPS (Massachusetts)
009 = County FIPS

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.

Census ACS API — Python 25009
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, ...]
SQL — filtering by county FIPS 25009
-- 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
R — tidycensus 25009
library(tidycensus)

get_acs(
  geography = "county",
  variables = c(income = "B19013_001E", pop = "B01003_001E"),
  state     = "25",
  county    = "009",
  year      = 2022
)
Zero-padding reminder: FIPS codes must always be stored and compared as zero-padded strings. 25 (not 25) and 009 (not 9) — losing the leading zeros is one of the most common data-join bugs in federal datasets. Full guide →

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.

Other Counties in Massachusetts