Every ZIP code in the United States, with weather, radar, trivia and the numbers behind it. Five digits since 1963!

ZIP stands for Zone Improvement Plan. The codes went live on July 1, 1963.The lowest ZIP code is 00501 — the IRS in Holtsville, New York.The highest ZIP code is 99950, in Ketchikan, Alaska.Type 07734 into a calculator and turn it upside down: hELLO. It is Keansburg, New Jersey.12345 belongs to one company: General Electric in Schenectady, New York.The first digit is a region: 0 is New England and New Jersey, 9 is the West Coast, Alaska and Hawaii.Mr. ZIP, the cartoon mailman, was the mascot that sold the idea to America.ZIP+4 arrived in 1983 and can narrow a ZIP down to one side of one block.A ZIP code is a mail route, not a place: plenty of them cross county and even state lines.Play ZIP Hunt: guess the secret ZIP code of the day in six tries.
zipcodes.pro — STATE/WA/COUNTY/COLUMBIA

Columbia County, WA ZIP codes

Columbia County, WA has 2 ZIP codes, in 2 towns: 99328 and 99359. 2 more cross into it from neighbouring counties: 99347 and 99361.

The county seat is Dayton.

ZIP codes
2
Partly in it
2 more
Towns
2
County seat
Dayton
County FIPS
53013
Population
4,014
Median household income
$71,810
Land area
869 sq mi

Columbia County ZIP codes by town

Dayton (county seat)
99328

Each ZIP code is listed under the county most of its land lies in and the town the Postal Service names it for; a ZIP code's own page shows exactly how it is split.

ZIP codes partly in Columbia County

These ZIP codes lie mostly in a neighbouring county but each cover a twentieth or more of Columbia County.

Map of Columbia County ZIP codes

9932899359

The ZIP codes of Columbia County, shaded. Outlines are Census ZIP Code Tabulation Areas (2020), which approximate the mail routes; PO-box and single-address codes have no area and are not drawn. Click any area to open its ZIP code.

Columbia County in numbers

About 4,014 people live in Columbia County, in 1,862 households, the 38th most populous of Washington's 39 counties. The median household income is $71,810 a year, 27% below the Washington median of $98,141 (US: $80,734). The median owner-occupied home is valued at $271,200 (52% below the Washington median), and median gross rent is $985 a month. The median age is 49.6; 24.9% of adults 25 and over hold a bachelor's degree or higher (39.6% across Washington); the average commute takes 23 minutes.

Population4,014Columbia4,014
Households1,862Columbia1,862
Median age49.6Columbia49.6Washington38.3US 38.9
Median household income$71,810Columbia$71,810Washington$98,141US $80,734
Median home value$271,200Columbia$271,200Washington$564,600US $332,700
Median gross rent$985Columbia$985Washington$1,760US $1,413
Bachelor's degree or higher24.9%Columbia24.9%Washington39.6%US 35.7%
Mean commute23.0 minColumbia23.0 minWashington26.6 minUS 26.4 min
Population density5 / sq miColumbia5 / sq mi

U.S. Census Bureau, American Community Survey 2020–2024 5-year estimates. Survey estimates carry margins of error, wider for small places. Sources and methods.

Largest towns in Columbia County

Largest towns in Columbia County
TownZIP codesPopulation
Dayton 1 2,774
Starbuck 1 93

Population of the census place of that name where there is one, otherwise of the ZIP codes the Postal Service addresses by it. A town's ZIP codes can reach past the county line.

Neighbouring counties

Counties that share a ZIP code with Columbia County.

Not sure you are in Columbia County? What county am I in? answers from your location, near a county line included.

Every ZIP code in Columbia County, with figures

ZIP codes in Columbia County
ZIP City Type Population Median income Median home
99328 Dayton , WA Standard 3,646 $72,756 $272,100
99359 Starbuck , WA Standard 94 $61,000 $135,400

Cite this page

zipcodes.pro. “Columbia County ZIP codes.” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/state/wa/county/columbia

Underlying data is public domain or openly licensed — sources, vintages and licences.