⚠

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

66010 County FIPS Code

Guam

Guam · County seat: Hagåtña · Independent city (not a county)

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FIPS code 66010 is Guam, Guam. The state FIPS code for Guam is 66. This code is used in Census Bureau, BLS, EPA, HUD, and USDA federal datasets to identify this county.

County FIPS

66010

State FIPS

Urban/Rural

Nonmetro — urban 20K+, not adjacent to metro

RUCC 5

How This FIPS Code Works

66 010

66 = State FIPS (Guam)

010 = County FIPS

The 5-digit FIPS code 66010 is formed by combining the 2-digit state identifier 66 (Guam) with the 3-digit county identifier 010. Together they uniquely identify Guam in every US federal dataset. No two counties share the same 5-digit FIPS code.

Federal Datasets Using Code 66010

FIPS code 66010 appears as the county identifier in the following federal datasets. Analysts joining data across these sources use this code as the common geographic key.

Census Bureau ACS American Community Survey — demographics, income, housing for Guam Decennial Census Population counts from the 2020 and 2010 Census BLS QCEW Quarterly Census of Employment and Wages — jobs and payroll by county EPA Environmental Air quality monitors, Superfund sites, water data by county HUD Fair Market Rents Section 8 FMRs and housing assistance — county level USDA ERS Economic Research Service — county-level agricultural and rural data BEA Personal Income Bureau of Economic Analysis — per capita income by county CDC Health Statistics County-level mortality, disease, and health outcome data CMS Medicare Data Centers for Medicare & Medicaid Services county utilization data

Using FIPS Code 66010 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 66010

import requests

url = "https://api.census.gov/data/2022/acs/acs5"
params = {
    "get":  "NAME,B19013_001E,B01003_001E",
    "for":  "county:010",
    "in":   "state:66",
    "key":  "YOUR_CENSUS_API_KEY",
}
r = requests.get(url, params=params)
data = r.json()  # [[header...], [Guam, Guam, income, pop, ...]

SQL — filtering by county FIPS 66010

-- 5-digit combined FIPS (state + county)
SELECT * FROM your_table WHERE county_fips = '66010';

-- Some datasets store state and county separately
SELECT * FROM your_table
WHERE state_fips = '66'
  AND county_fips = '010';

-- ⚠ Never cast to integer — leading zeros are lost:
-- county_fips = 66010 is WRONG for this county

R — tidycensus 66010

library(tidycensus)

get_acs(
  geography = "county",
  variables = c(income = "B19013_001E", pop = "B01003_001E"),
  state     = "66",
  county    = "010",
  year      = 2022
)

Zero-padding reminder: FIPS codes must always be stored and compared as zero-padded strings. 66 (not 66) and 010 (not 10) — losing the leading zeros is one of the most common data-join bugs in federal datasets. Full guide →

ZIP Codes in Guam

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 Guam. Why FIPS ≠ ZIP →

ZIP Code	Land area share	County land total	% in county
96910	100.0%	—	100.0%
96913	100.0%	—	100.0%
96915	100.0%	—	100.0%
96916	100.0%	—	100.0%
96917	100.0%	—	100.0%
96928	100.0%	—	100.0%
96929	100.0%	—	100.0%