| 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 |
| Fayette County | 148 644 | 145 351 | 3 293 | 2.3 |
| Belle Vernon borough | 1 211 | 1 213 | - 2 | - 0.2 |
| Brownsville borough | 2 804 | 3 164 | - 360 | - 11.4 |
| Brownsville township | 769 | 847 | - 78 | - 9.2 |
| Bullskin township | 7 782 | 7 323 | 459 | 6.3 |
| Connellsville city | 9 146 | 9 229 | - 83 | - 0.9 |
| Connellsville township | 2 483 | 2 553 | - 70 | - 2.7 |
| Dawson borough | 451 | 535 | - 84 | - 15.7 |
| Dunbar borough | 1 219 | 1 213 | 6 | 0.5 |
| Dunbar township | 7 562 | 7 460 | 102 | 1.4 |
| Everson borough | 842 | 939 | - 97 | - 10.3 |
| Fairchance borough | 2 174 | 1 918 | 256 | 13.3 |
| Fayette City borough | 714 | 713 | 1 | 0.1 |
| Franklin township | 2 628 | 2 640 | - 12 | - 0.5 |
| Georges township | 6 752 | 6 525 | 227 | 3.5 |
| German township | 5 595 | 5 596 | - 1 | 0.0 |
| Henry Clay township | 1 984 | 1 860 | 124 | 6.7 |
| Jefferson township | 2 259 | 2 047 | 212 | 10.4 |
| Lower Tyrone township | 1 171 | 1 138 | 33 | 2.9 |
| Luzerne township | 4 683 | 4 904 | - 221 | - 4.5 |
| Markleysburg borough | 282 | 320 | - 38 | - 11.9 |
| Masontown borough | 3 611 | 3 759 | - 148 | - 3.9 |
| Menallen township | 4 644 | 4 739 | - 95 | - 2.0 |
| Newell borough | 551 | 518 | 33 | 6.4 |
| Nicholson township | 1 989 | 1 995 | - 6 | - 0.3 |
| North Union township | 14 140 | 13 910 | 230 | 1.7 |
| Ohiopyle borough | 77 | 81 | - 4 | - 4.9 |
| Perry township | 2 786 | 2 817 | - 31 | - 1.1 |
| Perryopolis borough | 1 764 | 1 833 | - 69 | - 3.8 |
| Point Marion borough | 1 333 | 1 344 | - 11 | - 0.8 |
| Redstone township | 6 397 | 6 459 | - 62 | - 1.0 |
| Saltlick township | 3 715 | 3 253 | 462 | 14.2 |
| Seven Springs borough | 1 | 0 | 1 | - |
| Smithfield borough | 854 | 1 000 | - 146 | - 14.6 |
| South Connellsville borough | 2 281 | 2 204 | 77 | 3.5 |
| South Union township | 11 337 | 10 223 | 1 114 | 10.9 |
| Springfield township | 3 111 | 2 968 | 143 | 4.8 |
| Springhill township | 2 974 | 2 800 | 174 | 6.2 |
| Stewart township | 743 | 734 | 9 | 1.2 |
| Uniontown city | 12 422 | 12 034 | 388 | 3.2 |
| Upper Tyrone township | 2 244 | 1 995 | 249 | 12.5 |
| Vanderbilt borough | 553 | 545 | 8 | 1.5 |
| Washington township | 4 461 | 4 613 | - 152 | - 3.3 |
| Wharton township | 4 145 | 3 390 | 755 | 22.3 |
| Source: U.S. Census Bureau | Prepared by: Pennsylvania State Data Center | |||