| County | Rank | Change (2020) ↓ | 2025 Pop. | 2020 Pop. |
|---|---|---|---|---|
| San Juan County | 1 | 19.35% | 845 | 708 |
| Custer County | 2 | 17.57% | 5,555 | 4,725 |
| Weld County | 3 | 14.42% | 379,274 | 331,467 |
| Elbert County | 4 | 14.29% | 29,952 | 26,207 |
| Douglas County | 5 | 11.8% | 402,849 | 360,327 |
| Chaffee County | 6 | 7.51% | 20,952 | 19,488 |
| Mineral County | 7 | 7.23% | 934 | 871 |
| Costilla County | 8 | 7.06% | 3,748 | 3,501 |
| Broomfield County | 9 | 6.88% | 79,617 | 74,494 |
| Ouray County | 10 | 6.7% | 5,209 | 4,882 |
| Bent County | 11 | 6.68% | 5,846 | 5,480 |
| Park County | 12 | 6.26% | 18,511 | 17,420 |
| Morgan County | 13 | 5.89% | 30,794 | 29,082 |
| Montrose County | 14 | 5.78% | 45,293 | 42,820 |
| Adams County | 15 | 5.72% | 550,269 | 520,517 |
| Delta County | 16 | 5.2% | 32,670 | 31,056 |
| Larimer County | 17 | 4.91% | 377,618 | 359,932 |
| Archuleta County | 18 | 4.71% | 14,057 | 13,425 |
| Montezuma County | 19 | 4.61% | 27,082 | 25,889 |
| Mesa County | 20 | 4.37% | 162,830 | 156,011 |
| Saguache County | 21 | 4.03% | 6,653 | 6,395 |
| Grand County | 22 | 3.75% | 16,337 | 15,747 |
| El Paso County | 23 | 3.38% | 758,610 | 733,804 |
| Dolores County | 24 | 3.35% | 2,409 | 2,331 |
| Gilpin County | 25 | 3.2% | 6,003 | 5,817 |
| La Plata County | 26 | 2.82% | 57,245 | 55,676 |
| Denver County | 27 | 2.65% | 736,671 | 717,620 |
| Garfield County | 28 | 2.61% | 63,413 | 61,803 |
| Arapahoe County | 29 | 2.54% | 671,972 | 655,312 |
| Alamosa County | 30 | 2.05% | 16,710 | 16,375 |
| Gunnison County | 31 | 2.01% | 17,286 | 16,946 |
| Routt County | 32 | 1.98% | 25,332 | 24,840 |
| Fremont County | 33 | 1.93% | 49,834 | 48,889 |
| Conejos County | 34 | 1.83% | 7,587 | 7,451 |
| Rio Blanco County | 35 | 1.64% | 6,628 | 6,521 |
| Huerfano County | 36 | 1.63% | 6,935 | 6,824 |
| Yuma County | 37 | 1.45% | 10,115 | 9,970 |
| Teller County | 38 | 1.08% | 25,013 | 24,745 |
| Pueblo County | 39 | 0.98% | 170,009 | 168,352 |
| Las Animas County | 40 | 0.98% | 14,642 | 14,500 |
| Kit Carson County | 41 | 0.92% | 7,128 | 7,063 |
| Prowers County | 42 | 0.87% | 12,125 | 12,020 |
| Lincoln County | 43 | 0.65% | 5,698 | 5,661 |
| Boulder County | 44 | 0.35% | 332,105 | 330,953 |
| Lake County | 45 | -0.57% | 7,371 | 7,413 |
| Jefferson County | 46 | -0.65% | 579,373 | 583,169 |
| Summit County | 47 | -0.96% | 30,940 | 31,239 |
| Phillips County | 48 | -0.99% | 4,486 | 4,531 |
| Logan County | 49 | -1.69% | 20,850 | 21,209 |
| Crowley County | 50 | -1.78% | 5,584 | 5,685 |
| Moffat County | 51 | -2.05% | 12,997 | 13,269 |
| Washington County | 52 | -2.72% | 4,683 | 4,814 |
| Eagle County | 53 | -2.87% | 54,068 | 55,663 |
| Kiowa County | 54 | -3.03% | 1,408 | 1,452 |
| Baca County | 55 | -3.19% | 3,371 | 3,482 |
| Cheyenne County | 56 | -3.44% | 1,686 | 1,746 |
| Clear Creek County | 57 | -3.54% | 9,029 | 9,360 |
| San Miguel County | 58 | -3.6% | 7,764 | 8,054 |
| Rio Grande County | 59 | -4.1% | 11,070 | 11,543 |
| Pitkin County | 60 | -4.43% | 16,596 | 17,365 |
| Otero County | 61 | -4.45% | 17,834 | 18,664 |
| Hinsdale County | 62 | -6.86% | 733 | 787 |
| Sedgwick County | 63 | -7.53% | 2,209 | 2,389 |
| Jackson County | 64 | -10.74% | 1,230 | 1,378 |
Colorado's counties show varied growth patterns from 2020 to 2025. San Juan County leads with 19.35% annualized growth, followed by Custer County (17.57%) and Weld County (14.42%). The largest counties are El Paso County (758,610), Denver County (736,671), and Arapahoe County (671,972). Of the 64 counties in Colorado, 44 are growing while 20 have experienced population decline. Overall, counties averaged 2.29% annualized growth, with total population growing by 3.91% annually.
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