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County ZIP codes · Kansas · FIPS 20201

Washington County, KS ZIP Codes

Washington County, Kansas has 15 ZIP codes (Census 2020 ZCTA-county file; GeoNames postal codes, October 2026), all residential. 11 of the residential ones lie mainly in Washington County and 4 mainly in a neighboring county; 8 cross the county line. Median household income ranges from $55,284 in 66938 (Clyde) to $69,688 in 66945 (Hanover) (Census Bureau, ACS 2020-2024).

  • ACS2020-24
  • Census2020

Where are the ZIP codes of Washington County?

66412 · Bremen: $87k66548 · Waterville: $71k66933 · Barnes: $56k66937 · Clifton: $64k66938 · Clyde: $55k66943 · Greenleaf: $68k66944 · Haddam: $76k66945 · Hanover: $70k66946 · Hollenberg: $54k66953 · Linn: $66k66955 · Mahaska: $86k66958 · Morrowville: $78k66960 · Narka: $50k66962 · Palmer: $75k66968 · Washington: $59k66938669376696866945669586695366548669446694366933669556696266412669606694666412 · Bremen: $87k66548 · Waterville: $71k66933 · Barnes: $56k66937 · Clifton: $64k66938 · Clyde: $55k66943 · Greenleaf: $68k66944 · Haddam: $76k66945 · Hanover: $70k66946 · Hollenberg: $54k66953 · Linn: $66k66955 · Mahaska: $86k66958 · Morrowville: $78k66960 · Narka: $50k66962 · Palmer: $75k66968 · Washington: $59k66938669376696866945669586695366548669446694366933669556696266412669606694666412 · Bremen: $87k66548 · Waterville: $71k66933 · Barnes: $56k66937 · Clifton: $64k66938 · Clyde: $55k66943 · Greenleaf: $68k66944 · Haddam: $76k66945 · Hanover: $70k66946 · Hollenberg: $54k66953 · Linn: $66k66955 · Mahaska: $86k66958 · Morrowville: $78k66960 · Narka: $50k66962 · Palmer: $75k66968 · Washington: $59k66938669376696866945669586695366548669436695566962664126696066946
The residential ZIP codes of Washington 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?

They carry 15 postal town names.

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

All 15 residential ZIP codes in Washington County

11 ZIP codes lie mainly in Washington County; 4 more reach into it from a neighboring county and follow the first table.

Residential ZIP codes mainly in Washington County, largest first; "In this county" is the share of the ZIP's land in the county
In this county
66968 Washington 1,454 11 $59k $125k 100%
66945 Hanover 1,063 11 $70k $118k 99%
66937 Clifton 691 5 $64k $100k 54%
66953 Linn 628 9 $66k $109k 100%
66943 Greenleaf 568 6 $68k $117k 100%
66933 Barnes 345 4 $56k $86k 95%
66944 Haddam 304 3 $76k – 100%
66962 Palmer 302 6 $75k $304k 78%
66958 Morrowville 198 3 $78k $75k 100%
66946 Hollenberg 161 3 $54k $122k 100%
66955 Mahaska 47 1 $86k – 78%

Partly in Washington County

Residential ZIP codes mainly in another county that reach at least 1% into Washington County, by their share here
In this county
66938 Clyde 1,191 10 $55k $80k 19%
66412 Bremen 644 13 $87k $179k 16%
66960 Narka 125 2 $50k $31k 5%
66548 Waterville 975 12 $71k $90k 3%

Download the 15 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?

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

Share of each ZIP code's land in Washington County and in the neighboring counties
ZIPIn WashingtonElsewhere
6693819%Cloud County 67%; Republic County 9%; Clay County 5%
6694599%
665483%Marshall County 95%; Riley County 2%
6693754%Clay County 46%
6641216%Marshall County 84%
6693395%Riley County 5%
6696278%Clay County 22%
669605%Republic County 95%
6695578%Thayer County 22%

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

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

The first three digits of a ZIP code name the sectional center, the mail processing plant that sorts it. Washington County's ZIP codes use 3 prefixes: 664, 665 and 669.

Three-digit prefixes of Washington 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 Washington County's
PrefixSectional centerHereAll codes
664 Kansas City, MO (SCF 640) 1 37
665 Kansas City, MO (SCF 640) 1 44
669 Wichita, KS (SCF 670) 13 34

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