53033 FipsDecoder
Independent city — not a county. Suffolk 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.
25025 County FIPS Code

Suffolk County

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

View on CensusDepth ↗

FIPS code 25025 is Suffolk County, Massachusetts. With a population of 785,443 (2022 ACS estimate), it ranks #4 in Massachusetts and #79 nationally. Suffolk 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

25025

State FIPS

25

MA

Population

785,443

2022 ACS · #79 nationally

Density

13,507.2/mi²

people per sq mile

Land Area

58

sq miles

Urban/Rural

Metro — 1M+ population

RUCC 1

How This FIPS Code Works

25 025
25 = State FIPS (Massachusetts)
025 = County FIPS

The 5-digit FIPS code 25025 is formed by combining the 2-digit state identifier 25 (Massachusetts) with the 3-digit county identifier 025. Together they uniquely identify Suffolk County in every US federal dataset. No two counties share the same 5-digit FIPS code.

Census ACS Data for FIPS 25025

From the 2022 ACS 5-year estimates — the same values you'd retrieve by querying the Census API with county FIPS 25025.

Median Household Income

$87,669

ACS B19013_001E

Poverty Rate

17.0%

ACS B17001 (below poverty level)

Median Age

33.6

ACS B01002_001E

Metropolitan Area

Adjacent Counties (4)

Counties that share a border with Suffolk County. Useful for regional analysis — these are the geographies you'd typically include when studying labor markets, commuting zones, or environmental spillovers around FIPS 25025.

Federal Datasets Using Code 25025

FIPS code 25025 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 25025 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 25025
import requests

url = "https://api.census.gov/data/2022/acs/acs5"
params = {
    "get":  "NAME,B19013_001E,B01003_001E",
    "for":  "county:025",
    "in":   "state:25",
    "key":  "YOUR_CENSUS_API_KEY",
}
r = requests.get(url, params=params)
data = r.json()  # [[header...], [Suffolk County, Massachusetts, income, pop, ...]
SQL — filtering by county FIPS 25025
-- 5-digit combined FIPS (state + county)
SELECT * FROM your_table WHERE county_fips = '25025';

-- Some datasets store state and county separately
SELECT * FROM your_table
WHERE state_fips = '25'
  AND county_fips = '025';

-- ⚠ Never cast to integer — leading zeros are lost:
-- county_fips = 25025 is WRONG for this county
R — tidycensus 25025
library(tidycensus)

get_acs(
  geography = "county",
  variables = c(income = "B19013_001E", pop = "B01003_001E"),
  state     = "25",
  county    = "025",
  year      = 2022
)
Zero-padding reminder: FIPS codes must always be stored and compared as zero-padded strings. 25 (not 25) and 025 (not 25) — losing the leading zeros is one of the most common data-join bugs in federal datasets. Full guide →

ZIP Codes in Suffolk 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 Suffolk County. Why FIPS ≠ ZIP →

ZIP Code % in county
02108 100.0%
02109 100.0%
02110 100.0%
02111 100.0%
02113 100.0%
02114 100.0%
02115 100.0%
02116 100.0%
02118 100.0%
02119 100.0%
02120 100.0%
02121 100.0%
02122 100.0%
02124 100.0%
02125 100.0%
02126 100.0%
02127 100.0%
02128 100.0%
02129 100.0%
02130 100.0%
02131 100.0%
02132 100.0%
02133 100.0%
02134 100.0%
02135 100.0%
02136 100.0%
02163 100.0%
02199 100.0%
02203 100.0%
02205 100.0%

Showing top 30 of 39 ZIP codes by residential address share.

Other Counties in Massachusetts