(Links below lead to Quick Facts for Wyoming Counties: People, Business & Geography at U.S. Census Bureau.)
| Area | 7/1/2009 | 7/1/2008 | 7/1/2007 | 7/1/2006 | 7/1/2005 | 7/1/2004 | 7/1/2003 | 7/1/2002 | 7/1/2001 | 7/1/2000 | Census 2000 |
| Wyoming | 544,270 | 532,981 | 523,414 | 512,841 | 506,242 | 502,988 | 499,189 | 497,069 | 492,982 | 493,958 | 493,782 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Albany County | 33,979 | 33,099 | 32,479 | 32,757 | 32,610 | 32,752 | 32,484 | 32,275 | 32,209 | 31,914 | 32,014 |
| Big Horn County | 11,581 | 11,441 | 11,375 | 11,245 | 11,218 | 11,260 | 11,102 | 11,186 | 11,233 | 11,411 | 11,461 |
| Campbell County | 43,967 | 41,474 | 40,462 | 38,487 | 37,061 | 36,260 | 36,086 | 35,869 | 34,526 | 33,937 | 33,698 |
| Carbon County | 15,720 | 15,564 | 15,397 | 15,042 | 15,012 | 15,185 | 15,183 | 15,224 | 15,185 | 15,579 | 15,639 |
| Converse County | 13,578 | 13,263 | 12,874 | 12,627 | 12,453 | 12,243 | 12,151 | 12,156 | 11,981 | 12,097 | 12,052 |
| Crook County | 6,653 | 6,554 | 6,373 | 6,093 | 6,017 | 5,929 | 5,888 | 5,867 | 5,748 | 5,897 | 5,887 |
| Fremont County | 38,719 | 38,057 | 37,368 | 36,739 | 36,277 | 35,943 | 35,800 | 35,801 | 35,606 | 35,817 | 35,804 |
| Goshen County | 12,319 | 12,159 | 12,078 | 12,063 | 12,067 | 12,153 | 12,132 | 12,218 | 12,388 | 12,544 | 12,538 |
| Hot Springs County | 4,590 | 4,519 | 4,501 | 4,505 | 4,502 | 4,552 | 4,578 | 4,711 | 4,754 | 4,865 | 4,882 |
| Johnson County | 8,531 | 8,403 | 8,094 | 7,748 | 7,646 | 7,523 | 7,472 | 7,354 | 7,155 | 7,101 | 7,075 |
| Laramie County | 88,854 | 87,759 | 86,601 | 85,974 | 85,270 | 85,195 | 84,287 | 83,144 | 82,392 | 81,745 | 81,607 |
| Lincoln County | 16,995 | 16,681 | 16,178 | 15,727 | 15,345 | 15,090 | 14,787 | 14,644 | 14,588 | 14,614 | 14,573 |
| Natrona County | 74,508 | 73,057 | 71,817 | 70,259 | 69,442 | 68,659 | 67,957 | 67,371 | 66,873 | 66,554 | 66,533 |
| Niobrara County | 2,366 | 2,364 | 2,337 | 2,234 | 2,229 | 2,249 | 2,226 | 2,247 | 2,325 | 2,387 | 2,407 |
| Park County | 27,976 | 27,626 | 27,214 | 26,790 | 26,361 | 26,063 | 25,957 | 25,740 | 25,678 | 25,806 | 25,786 |
| Platte County | 8,196 | 8,267 | 8,367 | 8,425 | 8,463 | 8,560 | 8,571 | 8,694 | 8,736 | 8,748 | 8,807 |
| Sheridan County | 29,163 | 28,601 | 27,947 | 27,476 | 27,121 | 26,985 | 26,962 | 26,871 | 26,646 | 26,591 | 26,560 |
| Sublette County | 8,792 | 8,338 | 7,838 | 7,166 | 6,870 | 6,569 | 6,315 | 6,144 | 5,898 | 5,946 | 5,920 |
| Sweetwater County | 41,226 | 39,942 | 39,320 | 37,948 | 37,266 | 36,854 | 36,559 | 36,831 | 36,566 | 37,484 | 37,613 |
| Teton County | 20,710 | 20,541 | 20,073 | 19,666 | 19,343 | 19,238 | 18,890 | 18,727 | 18,594 | 18,367 | 18,251 |
| Uinta County | 20,927 | 20,537 | 20,071 | 19,631 | 19,431 | 19,419 | 19,440 | 19,567 | 19,406 | 19,662 | 19,742 |
| Washakie County | 7,911 | 7,807 | 7,805 | 7,671 | 7,763 | 7,754 | 7,822 | 7,890 | 8,023 | 8,257 | 8,289 |
| Weston County | 7,009 | 6,928 | 6,845 | 6,568 | 6,475 | 6,553 | 6,540 | 6,538 | 6,472 | 6,635 | 6,644 |
Source: Population Division, U.S. Census Bureau