53033 FipsDecoder
23003 County FIPS Code

Aroostook County

Maine · County seat: Houlton · Active county or equivalent

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FIPS code 23003 is Aroostook County, Maine. With a population of 67,237 (2022 ACS estimate), it ranks #6 in Maine and #798 nationally. The state FIPS code for Maine is 23. This code is used in Census Bureau, BLS, EPA, HUD, and USDA federal datasets to identify this county.

County FIPS

23003

State FIPS

23

ME

Population

67,237

2022 ACS · #798 nationally

Density

10.1/mi²

people per sq mile

Land Area

6,671

sq miles

Urban/Rural

Nonmetro — urban 2.5K–19.9K, not adjacent to metro

RUCC 7

How This FIPS Code Works

23 003
23 = State FIPS (Maine)
003 = County FIPS

The 5-digit FIPS code 23003 is formed by combining the 2-digit state identifier 23 (Maine) with the 3-digit county identifier 003. Together they uniquely identify Aroostook County in every US federal dataset. No two counties share the same 5-digit FIPS code.

Census ACS Data for FIPS 23003

From the 2022 ACS 5-year estimates — the same values you'd retrieve by querying the Census API with county FIPS 23003.

Median Household Income

$50,843

ACS B19013_001E

Poverty Rate

15.0%

ACS B17001 (below poverty level)

Median Age

48.5

ACS B01002_001E

Adjacent Counties (4)

Counties that share a border with Aroostook County. Useful for regional analysis — these are the geographies you'd typically include when studying labor markets, commuting zones, or environmental spillovers around FIPS 23003.

Federal Datasets Using Code 23003

FIPS code 23003 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 23003 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 23003
import requests

url = "https://api.census.gov/data/2022/acs/acs5"
params = {
    "get":  "NAME,B19013_001E,B01003_001E",
    "for":  "county:003",
    "in":   "state:23",
    "key":  "YOUR_CENSUS_API_KEY",
}
r = requests.get(url, params=params)
data = r.json()  # [[header...], [Aroostook County, Maine, income, pop, ...]
SQL — filtering by county FIPS 23003
-- 5-digit combined FIPS (state + county)
SELECT * FROM your_table WHERE county_fips = '23003';

-- Some datasets store state and county separately
SELECT * FROM your_table
WHERE state_fips = '23'
  AND county_fips = '003';

-- ⚠ Never cast to integer — leading zeros are lost:
-- county_fips = 23003 is WRONG for this county
R — tidycensus 23003
library(tidycensus)

get_acs(
  geography = "county",
  variables = c(income = "B19013_001E", pop = "B01003_001E"),
  state     = "23",
  county    = "003",
  year      = 2022
)
Zero-padding reminder: FIPS codes must always be stored and compared as zero-padded strings. 23 (not 23) and 003 (not 3) — losing the leading zeros is one of the most common data-join bugs in federal datasets. Full guide →

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

ZIP Code % in county
04787 100.0%
04779 100.0%
04780 100.0%
04781 100.0%
04783 100.0%
04785 100.0%
04786 100.0%
04471 100.0%
04730 100.0%
04734 100.0%
04735 100.0%
04736 100.0%
04737 100.0%
04739 100.0%
04740 100.0%
04742 100.0%
04743 100.0%
04745 100.0%
04746 100.0%
04747 100.0%
04750 100.0%
04756 100.0%
04757 100.0%
04758 100.0%
04760 100.0%
04761 100.0%
04762 100.0%
04763 100.0%
04764 100.0%
04766 100.0%

Showing top 30 of 42 ZIP codes by residential address share.

Other Counties in Maine