| 2010 Population and Percent Change by County | |||
| "-" refers to geographies which did not exist during the 2000 census | |||
| County | 2000_Population | 2010_Population | % Change |
| State | 4,301,261 | 5,029,196 | 16.92% |
| Adams | 363,857 | 441,603 | 21.37% |
| Alamosa | 14,966 | 15,445 | 3.20% |
| Arapahoe | 487,967 | 572,003 | 17.22% |
| Archuleta | 9,898 | 12,084 | 22.09% |
| Baca | 4,517 | 3,788 | -16.14% |
| Bent | 5,998 | 6,499 | 8.35% |
| Boulder | 291,288 | 294,567 | 1.13% |
| Broomfield | - | 55,889 | - |
| Chaffee | 16,242 | 17,809 | 9.65% |
| Cheyenne | 2,231 | 1,836 | -17.71% |
| Clear Creek | 9,322 | 9,088 | -2.51% |
| Conejos | 8,400 | 8,256 | -1.71% |
| Costilla | 3,663 | 3,524 | -3.79% |
| Crowley | 5,518 | 5,823 | 5.53% |
| Custer | 3,503 | 4,255 | 21.47% |
| Delta | 27,834 | 30,952 | 11.20% |
| Denver | 554,636 | 600,158 | 8.21% |
| Dolores | 1,844 | 2,064 | 11.93% |
| Douglas | 175,766 | 285,465 | 62.41% |
| Eagle | 41,659 | 52,197 | 25.30% |
| Elbert | 19,872 | 23,086 | 16.17% |
| El Paso | 516,929 | 622,263 | 20.38% |
| Fremont | 46,145 | 46,824 | 1.47% |
| Garfield | 43,791 | 56,389 | 28.77% |
| Gilpin | 4,757 | 5,441 | 14.38% |
| Grand | 12,442 | 14,843 | 19.30% |
| Gunnison | 13,956 | 15,324 | 9.80% |
| Hinsdale | 790 | 843 | 6.71% |
| Huerfano | 7,862 | 6,711 | -14.64% |
| Jackson | 1,577 | 1,394 | -11.60% |
| Jefferson | 527,056 | 534,543 | 1.42% |
| Kiowa | 1,622 | 1,398 | -13.81% |
| Kit Carson | 8,011 | 8,270 | 3.23% |
| Lake | 7,812 | 7,310 | -6.43% |
| La Plata | 43,941 | 51,334 | 16.82% |
| Larimer | 251,494 | 299,630 | 19.14% |
| Las Animas | 15,207 | 15,507 | 1.97% |
| Lincoln | 6,087 | 5,467 | -10.19% |
| Logan | 20,504 | 22,709 | 10.75% |
| Mesa | 116,255 | 146,723 | 26.21% |
| Mineral | 831 | 712 | -14.32% |
| Moffat | 13,184 | 13,795 | 4.63% |
| Montezuma | 23,830 | 25,535 | 7.15% |
| Montrose | 33,432 | 41,276 | 23.46% |
| Morgan | 27,171 | 28,159 | 3.64% |
| Otero | 20,311 | 18,831 | -7.29% |
| Ouray | 3,742 | 4,436 | 18.55% |
| Park | 14,523 | 16,206 | 11.59% |
| Phillips | 4,480 | 4,442 | -0.85% |
| Pitkin | 14,872 | 17,148 | 15.30% |
| Prowers | 14,483 | 12,551 | -13.34% |
| Pueblo | 141,472 | 159,063 | 12.43% |
| Rio Blanco | 5,986 | 6,666 | 11.36% |
| Rio Grande | 12,413 | 11,982 | -3.47% |
| Routt | 19,690 | 23,509 | 19.40% |
| Saguache | 5,917 | 6,108 | 3.23% |
| San Juan | 558 | 699 | 25.27% |
| San Miguel | 6,594 | 7,359 | 11.60% |
| Sedgwick | 2,747 | 2,379 | -13.40% |
| Summit | 23,548 | 27,994 | 18.88% |
| Teller | 20,555 | 23,350 | 13.60% |
| Washington | 4,926 | 4,814 | -2.27% |
| Weld | 180,936 | 252,825 | 39.73% |
| Yuma | 9,841 | 10,043 | 2.05% |
| *Source: US Census; DOLA State Demography Office |