Census Information
POPULATION IN UNION AND SURROUNDING COUNTIES: 1990 VS. 2000
| Centre | Clinton | Lycoming | Mifflin | North’d | Snyder | Union | |
| 1990 Population | 123,786 | 37,182 | 118,710 | 46,197 | 96,771 | 36,680 | 36,176 |
| 2000 Population | 135,758 | 37,914 | 120,044 | 46,486 | 94,556 | 94,556 | 41,624 |
* Data Source: U.S. Census Bureau, AmericanFactFinder
POPULATION OF UNION COUNTY MUNICIPALITIES, 2000
| Municipality | 1990 | 2000 |
| Buffalo Township | 2,877 | 3,207 |
| East Buffalo Township | 5,245 | 5,730 |
| Gregg Township | 1,114 | 4,687 |
| Hartleton | 246 | 260 |
| Hartley Township | 1,896 | 1,714 |
| Kelly Township | 4,561 | 4,502 |
| Lewis Township | 1,222 | 1,405 |
| Lewisburg | 5,785 | 5,620 |
| Limestone Township | 1,346 | 1,572 |
| Mifflinburg | 3,480 | 3,594 |
| New Berlin | 892 | 838 |
| Union Township | 1,300 | 1,427 |
| West Buffalo | 2,254 | 2,795 |
| White Deer | 3,958 | 4,273 |
* Data Source: U.S. Census Bureau