53033 FipsDecoder
24037 County FIPS Code

St. Mary's County

Maryland · County seat: Leonardtown · Active county or equivalent

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FIPS code 24037 is St. Mary's County, Maryland. With a population of 113,814 (2022 ACS estimate), it ranks #12 in Maryland and #541 nationally. St. Mary's County is part of the Lexington Park, MD. The state FIPS code for Maryland is 24. This code is used in Census Bureau, BLS, EPA, HUD, and USDA federal datasets to identify this county.

County FIPS

24037

State FIPS

24

MD

Population

113,814

2022 ACS · #541 nationally

Density

318.7/mi²

people per sq mile

Land Area

357

sq miles

Urban/Rural

Metro — under 250K population

RUCC 3

How This FIPS Code Works

24 037
24 = State FIPS (Maryland)
037 = County FIPS

The 5-digit FIPS code 24037 is formed by combining the 2-digit state identifier 24 (Maryland) with the 3-digit county identifier 037. Together they uniquely identify St. Mary's County in every US federal dataset. No two counties share the same 5-digit FIPS code.

Census ACS Data for FIPS 24037

From the 2022 ACS 5-year estimates — the same values you'd retrieve by querying the Census API with county FIPS 24037.

Median Household Income

$113,668

ACS B19013_001E

Poverty Rate

7.6%

ACS B17001 (below poverty level)

Median Age

37.0

ACS B01002_001E

Metropolitan Area

Adjacent Counties (6)

Counties that share a border with St. Mary's County. Useful for regional analysis — these are the geographies you'd typically include when studying labor markets, commuting zones, or environmental spillovers around FIPS 24037.

Federal Datasets Using Code 24037

FIPS code 24037 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 24037 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 24037
import requests

url = "https://api.census.gov/data/2022/acs/acs5"
params = {
    "get":  "NAME,B19013_001E,B01003_001E",
    "for":  "county:037",
    "in":   "state:24",
    "key":  "YOUR_CENSUS_API_KEY",
}
r = requests.get(url, params=params)
data = r.json()  # [[header...], [St. Mary's County, Maryland, income, pop, ...]
SQL — filtering by county FIPS 24037
-- 5-digit combined FIPS (state + county)
SELECT * FROM your_table WHERE county_fips = '24037';

-- Some datasets store state and county separately
SELECT * FROM your_table
WHERE state_fips = '24'
  AND county_fips = '037';

-- ⚠ Never cast to integer — leading zeros are lost:
-- county_fips = 24037 is WRONG for this county
R — tidycensus 24037
library(tidycensus)

get_acs(
  geography = "county",
  variables = c(income = "B19013_001E", pop = "B01003_001E"),
  state     = "24",
  county    = "037",
  year      = 2022
)
Zero-padding reminder: FIPS codes must always be stored and compared as zero-padded strings. 24 (not 24) and 037 (not 37) — losing the leading zeros is one of the most common data-join bugs in federal datasets. Full guide →

ZIP Codes in St. Mary's 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 St. Mary's County. Why FIPS ≠ ZIP →

ZIP Code % in county
20692 100.0%
20609 100.0%
20618 100.0%
20619 100.0%
20620 100.0%
20621 100.0%
20690 100.0%
20606 100.0%
20624 100.0%
20626 100.0%
20628 100.0%
20630 100.0%
20634 100.0%
20636 100.0%
20650 100.0%
20653 100.0%
20656 100.0%
20660 100.0%
20667 100.0%
20670 100.0%
20674 100.0%
20680 100.0%
20684 100.0%
20686 100.0%
20687 100.0%
20659 95.9%
20622 16.7%

Other Counties in Maryland