| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Peters | 1 | 23,257 | 22,968 | -0.02% | 1,193 | 20 | Township |
| North Strabane | 2 | 17,712 | 15,833 | 1.6% | 650 | 27 | Township |
| Washington | 3 | 15,584 | 14,882 | 0.43% | 399 | 39 | Township |
| Cecil | 4 | 15,270 | 14,642 | 0.53% | 579 | 26 | Township |
| Amity | 5 | 13,620 | 13,351 | 0.26% | 753 | 18 | Township |
| Washington | 6 | 13,451 | 13,131 | 0.55% | 4,592 | 3 | City |
| South Strabane | 7 | 9,709 | 9,678 | 0.38% | 422 | 23 | Township |
| Canonsburg | 8 | 9,490 | 9,718 | -0.41% | 4,108 | 2 | Borough |
| Chartiers | 9 | 9,344 | 8,699 | 0.45% | 380 | 25 | Township |
| Lawrence | 10 | 7,288 | 7,498 | -0.29% | 88 | 83 | Township |
| Washington | 11 | 6,775 | 6,869 | -0.21% | 212 | 32 | Township |
| Washington | 12 | 6,649 | 6,523 | 0.03% | 282 | 24 | Township |
| Union | 13 | 5,541 | 5,386 | 0.42% | 362 | 15 | Township |
| Carroll | 14 | 5,258 | 5,371 | -0.3% | 390 | 13 | Township |
| Washington | 15 | 5,241 | 5,156 | 0.36% | 294 | 18 | Township |
| North Franklin | 16 | 4,705 | 4,823 | -0.44% | 642 | 7 | Township |
| Washington | 17 | 4,577 | 4,457 | 0.18% | 325 | 14 | Township |
| Donora | 18 | 4,441 | 4,564 | -0.47% | 2,339 | 2 | Borough |
| California | 19 | 4,430 | 5,369 | -4.01% | 402 | 11 | Borough |
| Washington | 20 | 4,370 | 4,385 | 0.14% | 97 | 45 | Township |
| Smith | 21 | 4,196 | 4,240 | -0.21% | 122 | 34 | Township |
| Charleroi | 22 | 4,091 | 4,211 | -0.51% | 5,369 | 1 | Borough |
| Fallowfield | 23 | 4,031 | 4,122 | -0.25% | 189 | 21 | Township |
| Monongahela | 24 | 4,021 | 4,138 | -0.49% | 2,102 | 2 | City |
| Amwell | 25 | 3,642 | 3,669 | -0.11% | 81 | 45 | Township |
| Washington | 26 | 3,623 | 3,880 | -0.98% | 365 | 10 | Township |
| Washington | 27 | 3,183 | 3,132 | 0.25% | 103 | 31 | Township |
| South Franklin | 28 | 2,847 | 2,890 | -0.28% | 138 | 21 | Township |
| Washington | 29 | 2,666 | 2,582 | 0.57% | 95 | 28 | Township |
| Hickory | 30 | 2,322 | 2,319 | 0.78% | 147 | 16 | Township |
| Bentleyville | 31 | 2,317 | 2,370 | -0.39% | 627 | 4 | Borough |
| East Bethlehem | 32 | 2,228 | 2,289 | -0.45% | 440 | 5 | Township |
| Washington | 33 | 2,129 | 2,133 | -0.19% | 120 | 18 | Township |
| New Eagle | 34 | 2,011 | 2,053 | -0.35% | 1,979 | 1 | Borough |
| Buffalo | 35 | 1,964 | 1,982 | -0.1% | 96 | 20 | Township |
| Washington | 36 | 1,841 | 1,890 | -0.22% | 39 | 48 | Township |
| Washington | 37 | 1,832 | 1,859 | -0.16% | 56 | 33 | Township |
| East Washington | 38 | 1,805 | 1,854 | -0.5% | 4,020 | 0 | Borough |
| Washington | 39 | 1,784 | 1,752 | 0.28% | 75 | 24 | Township |
| Washington | 40 | 1,763 | 1,768 | 0.17% | 37 | 48 | Township |
| Washington | 41 | 1,626 | 1,648 | -0.49% | 43 | 38 | Township |
| Lawrence | 42 | 1,623 | 1,614 | 0.31% | 47 | 34 | Township |
| North Bethlehem | 43 | 1,536 | 1,561 | -0.32% | 70 | 22 | Township |
| West Pike Run | 44 | 1,497 | 1,538 | -0.47% | 92 | 16 | Township |
| Independence | 45 | 1,479 | 1,502 | -0.27% | 57 | 26 | Township |
| Monongahela | 46 | 1,403 | 1,481 | -0.85% | 80 | 17 | Township |
| Burgettstown | 47 | 1,383 | 1,411 | -0.5% | 2,223 | 1 | Borough |
| Cross Creek | 48 | 1,355 | 1,375 | -0.22% | 49 | 28 | Township |
| Washington | 49 | 1,305 | 1,340 | -0.46% | 69 | 19 | Township |
| East Finley | 50 | 1,290 | 1,284 | 0.31% | 37 | 35 | Township |
| West Bethlehem | 51 | 1,280 | 1,307 | -0.31% | 57 | 22 | Township |
| North Charleroi | 52 | 1,276 | 1,313 | -0.55% | 4,965 | 0 | Borough |
| Washington | 53 | 1,230 | 1,279 | -0.49% | 49 | 25 | Township |
| Houston | 54 | 1,120 | 1,153 | -0.53% | 2,725 | 0 | Borough |
| Amity | 55 | 975 | 985 | -0.1% | 35 | 28 | Township |
| Midway | 56 | 906 | 918 | -0.22% | 2,059 | 0 | Borough |
| Ellsworth | 57 | 894 | 921 | -0.56% | 1,210 | 1 | Borough |
| Washington | 58 | 894 | 928 | 0% | 33 | 27 | Township |
| Washington | 59 | 868 | 889 | 0.23% | 39 | 22 | Township |
| Washington | 60 | 863 | 843 | 0.12% | 65 | 13 | Township |
| West Finley | 61 | 841 | 811 | 0.48% | 21 | 39 | Township |
| Washington | 62 | 771 | 750 | 0.65% | 43 | 18 | Township |
| Claysville | 63 | 703 | 720 | -0.42% | 2,275 | 0 | Borough |
| Washington | 64 | 702 | 707 | 0.72% | 43 | 16 | Township |
| Roscoe | 65 | 697 | 717 | -0.57% | 3,830 | 0 | Borough |
| Blaine | 66 | 632 | 632 | 0.48% | 53 | 12 | Township |
| Cokeburg | 67 | 604 | 619 | -0.49% | 1,716 | 0 | Borough |
| Allenport | 68 | 466 | 481 | -0.64% | 219 | 2 | Borough |
| Stockdale | 69 | 411 | 424 | -0.72% | 1,593 | 0 | Borough |
| Long Branch | 70 | 408 | 418 | -0.49% | 128 | 3 | Borough |
| Beallsville | 71 | 387 | 397 | -0.51% | 159 | 2 | Borough |
| Hickory | 72 | 387 | 415 | -1.02% | 10 | 38 | Township |
| Marianna | 73 | 384 | 396 | -0.52% | 196 | 2 | Borough |
| Dunlevy | 74 | 362 | 369 | -0.28% | 680 | 1 | Borough |
| Finleyville | 75 | 358 | 369 | -0.56% | 2,144 | 0 | Borough |
| Daisytown | 76 | 281 | 293 | -0.71% | 1,206 | 0 | Borough |
| Elco | 77 | 256 | 264 | -0.39% | 918 | 0 | Borough |
| Twilight | 78 | 235 | 241 | -0.42% | 146 | 2 | Borough |
| Coal Center | 79 | 110 | 112 | 0% | 965 | 0 | Borough |
| West Middletown | 80 | 107 | 107 | 0% | 264 | 0 | Borough |
| Green Hills | 81 | 17 | 17 | 0% | 18 | 1 | Borough |
Peters is the largest city in Washington County, with a population of 23,257.
Green Hills is the smallest city in Washington County, with a population of 17.
There are 81 cities in Washington County, Pennsylvania.