Identifiers: city · borough · CDP
| Rank | Community | Population |
|---|---|---|
| 1 | New Castle (city), PA | 21,926 |
| 2 | Hermitage (city), PA | 16,230 |
| 3 | Sharon (city), PA | 13,147 |
| 4 | Grove City (borough), PA | 7,871 |
| 5 | Greenville (borough), PA | 5,540 |
| 6 | Farrell (city), PA | 4,258 |
| 7 | Zelienople (borough), PA | 3,912 |
| 8 | Slippery Rock (borough), PA | 3,081 |
| 9 | Slippery Rock University (CDP), PA | 2,397 |
| 10 | Oakwood (CDP), PA | 2,215 |
| 11 | New Wilmington (borough), PA | 2,092 |
| 12 | Mercer (borough), PA | 1,982 |
| 13 | Oakland (CDP), PA | 1,437 |
| 14 | New Castle Northwest (CDP), PA | 1,397 |
| 15 | Prospect (borough), PA | 1,123 |
| 16 | Ellport (borough), PA | 1,082 |
| 17 | Lake Latonka (CDP), PA | 951 |
| 18 | Stoneboro (borough), PA | 945 |
| 19 | Harmony (borough), PA | 942 |
| 20 | Unionville (CDP), PA | 849 |
Identifiers: city · borough · CDP
| Rank | Community | Population |
|---|---|---|
| 1 | Hermitage (city), PA | 16,230 |
| 2 | Sharon (city), PA | 13,147 |
| 3 | Grove City (borough), PA | 7,871 |
| 4 | Greenville (borough), PA | 5,540 |
| 5 | Farrell (city), PA | 4,258 |
| 6 | Sharpsville (borough), PA | 4,255 |
| 7 | Slippery Rock (borough), PA | 3,081 |
| 8 | Slippery Rock University (CDP), PA | 2,397 |
| 9 | New Wilmington (borough), PA | 2,092 |
| 10 | Mercer (borough), PA | 1,982 |
| 11 | Reynolds Heights (CDP), PA | 1,974 |
| 12 | Prospect (borough), PA | 1,123 |
| 13 | Lake Latonka (CDP), PA | 951 |
| 14 | Stoneboro (borough), PA | 945 |
| 15 | Unionville (CDP), PA | 849 |
| 16 | Harrisville (borough), PA | 819 |
| 17 | West Middlesex (borough), PA | 818 |
| 18 | Sandy Lake (borough), PA | 649 |
| 19 | Polk (borough), PA | 634 |
| 20 | Emlenton (borough), PA | 614 |