| 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 |
| Lycoming County | 120 044 | 118 710 | 1 334 | 1.1 |
| Anthony township | 904 | 727 | 177 | 24.3 |
| Armstrong township | 717 | 676 | 41 | 6.1 |
| Bastress township | 574 | 513 | 61 | 11.9 |
| Brady township | 494 | 822 | - 328 | - 39.9 |
| Brown township | 111 | 102 | 9 | 8.8 |
| Cascade township | 419 | 382 | 37 | 9.7 |
| Clinton township | 3 947 | 3 086 | 861 | 27.9 |
| Cogan House township | 974 | 807 | 167 | 20.7 |
| Cummings township | 355 | 334 | 21 | 6.3 |
| Duboistown borough | 1 280 | 1 201 | 79 | 6.6 |
| Eldred township | 2 178 | 2 055 | 123 | 6.0 |
| Fairfield township | 2 659 | 2 580 | 79 | 3.1 |
| Franklin township | 915 | 914 | 1 | 0.1 |
| Gamble township | 854 | 744 | 110 | 14.8 |
| Hepburn township | 2 836 | 2 834 | 2 | 0.1 |
| Hughesville borough | 2 220 | 2 049 | 171 | 8.3 |
| Jackson township | 414 | 421 | - 7 | - 1.7 |
| Jersey Shore borough | 4 482 | 4 353 | 129 | 3.0 |
| Jordan township | 878 | 871 | 7 | 0.8 |
| Lewis township | 1 139 | 1 194 | - 55 | - 4.6 |
| Limestone township | 2 136 | 1 893 | 243 | 12.8 |
| Loyalsock township | 10 876 | 10 644 | 232 | 2.2 |
| Lycoming township | 1 606 | 1 748 | - 142 | - 8.1 |
| McHenry township | 145 | 246 | - 101 | - 41.1 |
| McIntyre township | 539 | 588 | - 49 | - 8.3 |
| McNett township | 211 | 200 | 11 | 5.5 |
| Mifflin township | 1 145 | 1 110 | 35 | 3.2 |
| Mill Creek township | 572 | 477 | 95 | 19.9 |
| Montgomery borough | 1 695 | 1 631 | 64 | 3.9 |
| Montoursville borough | 4 777 | 4 983 | - 206 | - 4.1 |
| Moreland township | 1 036 | 984 | 52 | 5.3 |
| Muncy borough | 2 663 | 2 702 | - 39 | - 1.4 |
| Muncy township | 1 059 | 1 036 | 23 | 2.2 |
| Muncy Creek township | 3 487 | 3 401 | 86 | 2.5 |
| Nippenose township | 729 | 742 | - 13 | - 1.8 |
| Old Lycoming township | 5 508 | 5 526 | - 18 | - 0.3 |
| Penn township | 900 | 788 | 112 | 14.2 |
| Piatt township | 1 259 | 1 097 | 162 | 14.8 |
| Picture Rocks borough | 693 | 660 | 33 | 5.0 |
| Pine township | 329 | 290 | 39 | 13.4 |
| Plunketts Creek township | 771 | 905 | - 134 | - 14.8 |
| Porter township | 1 633 | 1 441 | 192 | 13.3 |
| Salladasburg borough | 260 | 301 | - 41 | - 13.6 |
| Shrewsbury township | 433 | 402 | 31 | 7.7 |
| South Williamsport borough | 6 412 | 6 496 | - 84 | - 1.3 |
| Susquehanna township | 993 | 1 046 | - 53 | - 5.1 |
| Upper Fairfield township | 1 854 | 1 774 | 80 | 4.5 |
| Washington township | 1 613 | 1 552 | 61 | 3.9 |
| Watson township | 550 | 565 | - 15 | - 2.7 |
| Williamsport city | 30 706 | 31 933 | - 1 227 | - 3.8 |
| Wolf township | 2 707 | 2 617 | 90 | 3.4 |
| Woodward township | 2 397 | 2 267 | 130 | 5.7 |
| Source: U.S. Census Bureau | Prepared by: Pennsylvania State Data Center | |||