| Population Change 1990-2000 | ||||
| County or Municipality | 2000 Population | 1990 Population | Population Change | Percent Change |
| Pennsylvania | 12 281 054 | 11 881 643 | 399 411 | 3.4 |
| Clinton County | 37 914 | 37 182 | 732 | 2.0 |
| Allison township | 198 | 191 | 7 | 3.7 |
| Avis borough | 1 492 | 1 506 | - 14 | - 0.9 |
| Bald Eagle township | 1 898 | 1 809 | 89 | 4.9 |
| Beech Creek borough | 717 | 716 | 1 | 0.1 |
| Beech Creek township | 1 010 | 1 007 | 3 | 0.3 |
| Castanea township | 1 233 | 1 188 | 45 | 3.8 |
| Chapman township | 993 | 978 | 15 | 1.5 |
| Colebrook township | 179 | 180 | - 1 | - 0.6 |
| Crawford township | 848 | 665 | 183 | 27.5 |
| Dunnstable township | 945 | 846 | 99 | 11.7 |
| East Keating township | 24 | 22 | 2 | 9.1 |
| Flemington borough | 1 319 | 1 321 | - 2 | - 0.2 |
| Gallagher township | 340 | 213 | 127 | 59.6 |
| Greene township | 1 464 | 1 153 | 311 | 27.0 |
| Grugan township | 52 | 52 | 0 | 0.0 |
| Lamar township | 2 450 | 2 345 | 105 | 4.5 |
| Leidy township | 229 | 214 | 15 | 7.0 |
| Lock Haven city | 9 149 | 9 230 | - 81 | - 0.9 |
| Logan township | 773 | 730 | 43 | 5.9 |
| Loganton borough | 435 | 443 | - 8 | - 1.8 |
| Mill Hall borough | 1 568 | 1 702 | - 134 | - 7.9 |
| Noyes township | 419 | 463 | - 44 | - 9.5 |
| Pine Creek township | 3 184 | 3 188 | - 4 | - 0.1 |
| Porter township | 1 419 | 1 437 | - 18 | - 1.3 |
| Renovo borough | 1 318 | 1 526 | - 208 | - 13.6 |
| South Renovo borough | 557 | 579 | - 22 | - 3.8 |
| Wayne township | 1 363 | 782 | 581 | 74.3 |
| West Keating township | 42 | 34 | 8 | 23.5 |
| Woodward township | 2 296 | 2 662 | - 366 | - 13.7 |
| Source: U.S. Census Bureau | Prepared by: Pennsylvania State Data Center | |||