County ZIP codes · Washington · FIPS 53013

Columbia County, WA ZIP Codes

Columbia County, Washington has 5 ZIP codes (Census 2020 ZCTA-county file; GeoNames postal codes, October 2026), all residential. 2 of the residential ones lie mainly in Columbia County and 3 mainly in a neighboring county; 3 cross the county line. Median household income ranges from $64,699 in 99347 (Pomeroy) to $91,367 in 99361 (Waitsburg) (Census Bureau, ACS 2020-2024).

ACS2020-24
Census2020

Where are the ZIP codes of Columbia County?

The residential ZIP codes of Columbia County (whole outlines, including the parts in neighboring counties), shaded by median household income in national fifths (ACS 2020-2024).<$54.1k$98.1k+no figure

Source: U.S. Census Bureau, 2020 ZCTA cartographic boundaries; ACS 2020-2024 5-year estimates (B19013).

How different are its ZIP codes?

99347 · $65k99361 · $91k

The middle half of its ranked ZIP codes (1,000+ people living in households) report median household incomes between $64,699 and $79,167.

They carry 5 postal town names: Dayton, Pomeroy, Waitsburg, Prescott, Starbuck.

Source: U.S. Census Bureau, ACS 2020-2024 5-year estimates (B19013).

All 5 residential ZIP codes in Columbia County

2 ZIP codes lie mainly in Columbia County; 3 more reach into it from a neighboring county and follow the first table.

Residential ZIP codes mainly in Columbia County, largest first; "In this county" is the share of the ZIP's land in the county
						In this county
99328	Dayton	3,646	6	$73k	$272k	100%
99359	Starbuck	94	2	$61k	$135k	100%

Partly in Columbia County

Residential ZIP codes mainly in another county that reach at least 1% into Columbia County, by their share here
						In this county
99361	Waitsburg	1,992	9	$91k	$296k	32%
99347	Pomeroy	2,512	3	$65k	$243k	10%
99348	Prescott	1,633	3	$79k	$237k	4%

Download the 5 ZIP codes as CSV

Source: U.S. Census Bureau, ACS 2020-2024 5-year estimates; county shares by land area (Census 2020 ZCTA-county relationship file).

Which ZIP codes cross the county line?

3 ZIP codes of Columbia County extend into another county. A ZIP code follows mail routes, not county borders.

Share of each ZIP code's land in Columbia County and in the neighboring counties
ZIP	In Columbia	Elsewhere
99347	10%	Garfield County89%; Whitman County2%
99361	32%	Walla Walla County68%
99348	4%	Walla Walla County96%

Source: U.S. Census Bureau, 2020 ZCTA-county relationship file (shares of land area).

Which first three digits do Columbia County's ZIP codes use?

The first three digits of a ZIP code name the sectional center, the mail processing plant that sorts it. Every ZIP code of Columbia County starts with 993.

Three-digit prefixes of Columbia County's ZIP codes, the sectional center for each (USPS labeling list L005, effective October 1, 2026) and how many of the prefix's codes are Columbia County's
Prefix	Sectional center	Here	All codes
993	Spokane, WA (SCF 990)	5	36

Source: U.S. Postal Service, labeling list L005 (3-digit ZIP Code prefix groups, SCF sortation), effective October 1, 2026.