53033 FipsDecoder
53033 County FIPS Code

King County

Washington · County seat: Seattle · Active county or equivalent

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FIPS code 53033 is King County, Washington. With a population of 2,254,371 (2022 ACS estimate), it ranks #1 in Washington and #13 nationally. King County is part of the Seattle-Tacoma-Bellevue, WA. The state FIPS code for Washington is 53. This code is used in Census Bureau, BLS, EPA, HUD, and USDA federal datasets to identify this county.

County FIPS

53033

State FIPS

53

WA

Population

2,254,371

2022 ACS · #13 nationally

Density

1,065.6/mi²

people per sq mile

Land Area

2,116

sq miles

Urban/Rural

Metro — 1M+ population

RUCC 1

How This FIPS Code Works

53 033
53 = State FIPS (Washington)
033 = County FIPS

The 5-digit FIPS code 53033 is formed by combining the 2-digit state identifier 53 (Washington) with the 3-digit county identifier 033. Together they uniquely identify King County in every US federal dataset. No two counties share the same 5-digit FIPS code.

Census ACS Data for FIPS 53033

From the 2022 ACS 5-year estimates — the same values you'd retrieve by querying the Census API with county FIPS 53033.

Median Household Income

$116,340

ACS B19013_001E

Poverty Rate

8.5%

ACS B17001 (below poverty level)

Median Age

37.2

ACS B01002_001E

Metropolitan Area

Adjacent Counties (6)

Counties that share a border with King County. Useful for regional analysis — these are the geographies you'd typically include when studying labor markets, commuting zones, or environmental spillovers around FIPS 53033.

Federal Datasets Using Code 53033

FIPS code 53033 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 53033 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 53033
import requests

url = "https://api.census.gov/data/2022/acs/acs5"
params = {
    "get":  "NAME,B19013_001E,B01003_001E",
    "for":  "county:033",
    "in":   "state:53",
    "key":  "YOUR_CENSUS_API_KEY",
}
r = requests.get(url, params=params)
data = r.json()  # [[header...], [King County, Washington, income, pop, ...]
SQL — filtering by county FIPS 53033
-- 5-digit combined FIPS (state + county)
SELECT * FROM your_table WHERE county_fips = '53033';

-- Some datasets store state and county separately
SELECT * FROM your_table
WHERE state_fips = '53'
  AND county_fips = '033';

-- ⚠ Never cast to integer — leading zeros are lost:
-- county_fips = 53033 is WRONG for this county
R — tidycensus 53033
library(tidycensus)

get_acs(
  geography = "county",
  variables = c(income = "B19013_001E", pop = "B01003_001E"),
  state     = "53",
  county    = "033",
  year      = 2022
)
Zero-padding reminder: FIPS codes must always be stored and compared as zero-padded strings. 53 (not 53) and 033 (not 33) — losing the leading zeros is one of the most common data-join bugs in federal datasets. Full guide →

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

ZIP Code % in county
98133 100.0%
98002 100.0%
98003 100.0%
98004 100.0%
98005 100.0%
98006 100.0%
98007 100.0%
98008 100.0%
98010 100.0%
98011 100.0%
98014 100.0%
98019 100.0%
98177 100.0%
98178 100.0%
98188 100.0%
98195 100.0%
98198 100.0%
98199 100.0%
98224 100.0%
98288 100.0%
98023 100.0%
98024 100.0%
98025 100.0%
98027 100.0%
98028 100.0%
98029 100.0%
98030 100.0%
98031 100.0%
98032 100.0%
98033 100.0%

Showing top 30 of 89 ZIP codes by residential address share.

Other Counties in Washington