| Zip Code | City | Population ↓ |
|---|---|---|
| 15301 | Washington | 50,183 |
| 15317 | Canonsburg | 43,435 |
| 15057 | McDonald | 17,440 |
| 15063 | Monongahela | 10,543 |
| 15022 | Charleroi | 10,248 |
| 15367 | Venetia | 9,500 |
| 15332 | Finleyville | 8,604 |
| 15417 | Brownsville | 7,886 |
| 15021 | Burgettstown | 6,699 |
| 15330 | Eighty Four | 5,539 |
| 15342 | Houston | 5,138 |
| 15033 | Donora | 4,622 |
| 15312 | Avella | 3,972 |
| 15323 | Claysville | 3,829 |
| 15419 | California | 3,796 |
| 15314 | Bentleyville | 3,528 |
| 15067 | New Eagle | 2,285 |
| 15321 | Cecil | 1,949 |
| 15423 | Coal Center | 1,889 |
| 15360 | Scenery Hill | 1,710 |
| 15019 | Bulger | 1,552 |
| 15333 | Fredericktown | 1,543 |
| 15376 | West Alexander | 1,508 |
| 15329 | Prosperity | 1,490 |
| 15345 | Marianna | 1,343 |
| 15340 | Hickory | 1,293 |
| 15055 | Lawrence | 1,146 |
| 15358 | Richeyville | 1,111 |
| 15311 | Amity | 1,033 |
| 15427 | Daisytown | 918 |
| 15060 | Midway | 906 |
| 15477 | Roscoe | 831 |
| 15324 | Cokeburg | 767 |
| 15331 | Ellsworth | 721 |
| 15377 | West Finley | 669 |
| 15363 | Strabane | 566 |
| 15350 | Muse | 521 |
| 15078 | Slovan | 516 |
| 15366 | Van Voorhis | 504 |
| 15054 | Langeloth | 447 |
| 15429 | Denbo | 444 |
| 15313 | Beallsville | 422 |
| 15368 | Vestaburg | 419 |
| 15432 | Dunlevy | 366 |
| 15004 | Atlasburg | 316 |
| 15434 | Elco | 272 |
| 15483 | Stockdale | 253 |
| 15038 | Elrama | 248 |
| 15412 | Allenport | 210 |
| 15365 | Taylorstown | 200 |
| 15361 | Southview | 123 |
| 15347 | Meadow Lands | 102 |
| 15379 | West Middletown | 71 |
| 15053 | Joffre | 70 |
| 15348 | Millsboro | 69 |
| 15378 | Westland | 0 |
The data shown reflect ZCTAs from the US Census. As of 2024, there are 56 ZCTAs in Washington County, Pennsylvania (US Census).