| County | Rank | Change (2020) ↓ | 2026 Pop. | 2020 Pop. |
|---|---|---|---|---|
| San Juan County | 1 | 22.74% | 869 | 708 |
| Custer County | 2 | 17.61% | 5,557 | 4,725 |
| Weld County | 3 | 17.3% | 388,803 | 331,467 |
| Elbert County | 4 | 16.47% | 30,522 | 26,207 |
| Douglas County | 5 | 14.26% | 411,703 | 360,327 |
| Costilla County | 6 | 8.83% | 3,810 | 3,501 |
| Broomfield County | 7 | 8.61% | 80,911 | 74,494 |
| Chaffee County | 8 | 8.39% | 21,124 | 19,488 |
| Bent County | 9 | 7.9% | 5,913 | 5,480 |
| Morgan County | 10 | 7.59% | 31,288 | 29,082 |
| Park County | 11 | 7.38% | 18,706 | 17,420 |
| Mineral County | 12 | 7.35% | 935 | 871 |
| Adams County | 13 | 7.12% | 557,565 | 520,517 |
| Ouray County | 14 | 6.94% | 5,221 | 4,882 |
| Montrose County | 15 | 6.91% | 45,780 | 42,820 |
| Delta County | 16 | 6.66% | 33,125 | 31,056 |
| Larimer County | 17 | 5.76% | 380,662 | 359,932 |
| Montezuma County | 18 | 5.54% | 27,323 | 25,889 |
| Mesa County | 19 | 5.38% | 164,400 | 156,011 |
| Grand County | 20 | 4.91% | 16,520 | 15,747 |
| Archuleta County | 21 | 4.3% | 14,002 | 13,425 |
| El Paso County | 22 | 4.18% | 764,448 | 733,804 |
| Gilpin County | 23 | 3.89% | 6,043 | 5,817 |
| Saguache County | 24 | 3.77% | 6,636 | 6,395 |
| Denver County | 25 | 3.72% | 744,323 | 717,620 |
| La Plata County | 26 | 3.58% | 57,667 | 55,676 |
| Arapahoe County | 27 | 3.31% | 677,026 | 655,312 |
| Garfield County | 28 | 3% | 63,659 | 61,803 |
| Lincoln County | 29 | 2.42% | 5,798 | 5,661 |
| Routt County | 30 | 2.34% | 25,421 | 24,840 |
| Conejos County | 31 | 2.34% | 7,625 | 7,451 |
| Prowers County | 32 | 2.27% | 12,293 | 12,020 |
| Alamosa County | 33 | 2.17% | 16,731 | 16,375 |
| Yuma County | 34 | 2.13% | 10,182 | 9,970 |
| Rio Blanco County | 35 | 1.96% | 6,649 | 6,521 |
| Gunnison County | 36 | 1.86% | 17,262 | 16,946 |
| Las Animas County | 37 | 1.83% | 14,766 | 14,500 |
| Teller County | 38 | 1.69% | 25,164 | 24,745 |
| Kit Carson County | 39 | 1.6% | 7,176 | 7,063 |
| Fremont County | 40 | 1.4% | 49,575 | 48,889 |
| Pueblo County | 41 | 1.07% | 170,152 | 168,352 |
| Boulder County | 42 | 0.9% | 333,948 | 330,953 |
| Dolores County | 43 | 0.86% | 2,351 | 2,331 |
| Huerfano County | 44 | 0.85% | 6,882 | 6,824 |
| Jefferson County | 45 | -0.51% | 580,213 | 583,169 |
| Lake County | 46 | -0.54% | 7,373 | 7,413 |
| Summit County | 47 | -0.77% | 30,998 | 31,239 |
| Phillips County | 48 | -1.04% | 4,484 | 4,531 |
| Logan County | 49 | -1.24% | 20,945 | 21,209 |
| Kiowa County | 50 | -1.93% | 1,424 | 1,452 |
| Crowley County | 51 | -2.06% | 5,568 | 5,685 |
| Baca County | 52 | -3.07% | 3,375 | 3,482 |
| Moffat County | 53 | -3.14% | 12,852 | 13,269 |
| Eagle County | 54 | -3.34% | 53,806 | 55,663 |
| Clear Creek County | 55 | -4.04% | 8,982 | 9,360 |
| San Miguel County | 56 | -4.28% | 7,709 | 8,054 |
| Washington County | 57 | -4.55% | 4,595 | 4,814 |
| Rio Grande County | 58 | -4.63% | 11,008 | 11,543 |
| Pitkin County | 59 | -4.7% | 16,549 | 17,365 |
| Cheyenne County | 60 | -4.93% | 1,660 | 1,746 |
| Otero County | 61 | -5.29% | 17,677 | 18,664 |
| Hinsdale County | 62 | -8.64% | 719 | 787 |
| Sedgwick County | 63 | -9.54% | 2,161 | 2,389 |
| Jackson County | 64 | -13.86% | 1,187 | 1,378 |
Colorado's counties show varied growth patterns from 2020 to 2026. San Juan County leads with 3.47% annualized growth, followed by Custer County (2.74%) and Weld County (2.69%). The largest counties are El Paso County (764,448), Denver County (744,323), and Arapahoe County (677,026). Of the 64 counties in Colorado, 44 are growing while 20 have experienced population decline. Overall, counties averaged 0.41% annualized growth, with total population growing by 0.8% annually.
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