| County | Rank | Change (2020) ↓ | 2025 Pop. | 2020 Pop. |
|---|---|---|---|---|
| Custer County | 1 | 25.51% | 5,928 | 4,723 |
| Elbert County | 2 | 17.23% | 30,734 | 26,216 |
| Weld County | 3 | 13.98% | 377,794 | 331,458 |
| Bent County | 4 | 12.64% | 6,165 | 5,473 |
| Dolores County | 5 | 12.36% | 2,619 | 2,331 |
| San Juan County | 6 | 11.67% | 794 | 711 |
| Mineral County | 7 | 10.98% | 970 | 874 |
| Douglas County | 8 | 10.97% | 399,844 | 360,323 |
| Chaffee County | 9 | 9.43% | 21,321 | 19,484 |
| Ouray County | 10 | 9.01% | 5,322 | 4,882 |
| Archuleta County | 11 | 8.68% | 14,589 | 13,424 |
| Saguache County | 12 | 6.59% | 6,810 | 6,389 |
| Park County | 13 | 6.26% | 18,509 | 17,418 |
| Fremont County | 14 | 5.82% | 51,722 | 48,878 |
| Broomfield County | 15 | 4.97% | 78,190 | 74,490 |
| Larimer County | 16 | 4.79% | 377,159 | 359,923 |
| Montrose County | 17 | 4.76% | 44,854 | 42,818 |
| Adams County | 18 | 4.72% | 545,077 | 520,500 |
| Costilla County | 19 | 4.34% | 3,654 | 3,502 |
| Mesa County | 20 | 3.83% | 161,981 | 156,011 |
| Grand County | 21 | 3.75% | 16,337 | 15,747 |
| Delta County | 22 | 3.42% | 32,118 | 31,056 |
| Morgan County | 23 | 3.32% | 30,040 | 29,076 |
| Gilpin County | 24 | 3.2% | 6,006 | 5,820 |
| Montezuma County | 25 | 2.98% | 26,659 | 25,887 |
| Garfield County | 26 | 2.94% | 63,609 | 61,794 |
| El Paso County | 27 | 2.6% | 751,453 | 732,384 |
| Alamosa County | 28 | 2.53% | 16,791 | 16,377 |
| Moffat County | 29 | 2.28% | 13,571 | 13,269 |
| Gunnison County | 30 | 2.2% | 17,323 | 16,950 |
| Huerfano County | 31 | 2.11% | 6,971 | 6,827 |
| Rio Blanco County | 32 | 1.37% | 6,609 | 6,520 |
| Washington County | 33 | 1.21% | 4,871 | 4,813 |
| Routt County | 34 | 0.87% | 25,048 | 24,832 |
| La Plata County | 35 | 0.79% | 56,115 | 55,673 |
| Denver County | 36 | 0.73% | 722,825 | 717,606 |
| Pueblo County | 37 | 0.59% | 169,322 | 168,337 |
| Phillips County | 38 | 0.11% | 4,532 | 4,527 |
| Arapahoe County | 39 | 0.06% | 655,645 | 655,272 |
| Lake County | 40 | -0.07% | 7,403 | 7,408 |
| Las Animas County | 41 | -0.47% | 14,422 | 14,490 |
| Crowley County | 42 | -0.6% | 5,654 | 5,688 |
| Kit Carson County | 43 | -0.65% | 7,016 | 7,062 |
| Conejos County | 44 | -0.83% | 7,389 | 7,451 |
| Jefferson County | 45 | -0.96% | 577,476 | 583,081 |
| Cheyenne County | 46 | -1.55% | 1,719 | 1,746 |
| Boulder County | 47 | -1.55% | 325,815 | 330,938 |
| Yuma County | 48 | -1.76% | 9,796 | 9,971 |
| Teller County | 49 | -2.48% | 24,131 | 24,744 |
| Sedgwick County | 50 | -2.68% | 2,325 | 2,389 |
| Summit County | 51 | -2.83% | 30,123 | 31,001 |
| Prowers County | 52 | -4.24% | 11,507 | 12,017 |
| Lincoln County | 53 | -4.27% | 5,420 | 5,662 |
| Logan County | 54 | -4.42% | 20,273 | 21,210 |
| Hinsdale County | 55 | -4.44% | 753 | 788 |
| Otero County | 56 | -4.7% | 17,786 | 18,664 |
| Eagle County | 57 | -5.3% | 52,707 | 55,657 |
| Rio Grande County | 58 | -5.64% | 10,890 | 11,541 |
| San Miguel County | 59 | -5.79% | 7,588 | 8,054 |
| Jackson County | 60 | -5.8% | 1,299 | 1,379 |
| Pitkin County | 61 | -6.51% | 16,226 | 17,355 |
| Clear Creek County | 62 | -7.3% | 8,707 | 9,393 |
| Baca County | 63 | -9.14% | 3,162 | 3,480 |
| Kiowa County | 64 | -11.75% | 1,284 | 1,455 |
Colorado's counties show varied growth patterns from 2020 to 2025. Custer County leads with 25.51% annualized growth, followed by Elbert County (17.23%) and Weld County (13.98%). The largest counties are El Paso County (751,453), Denver County (722,825), and Arapahoe County (655,645). Of the 64 counties in Colorado, 39 are growing while 25 have experienced population decline. Overall, counties averaged 2.03% annualized growth, with total population growing by 2.86% annually.