| County | Rank | Change (2020) ↓ | 2026 Pop. | 2020 Pop. |
|---|---|---|---|---|
| Elbert County | 1 | 21.03% | 31,724 | 26,211 |
| Custer County | 2 | 18.82% | 5,613 | 4,724 |
| Weld County | 3 | 16.33% | 385,572 | 331,434 |
| San Juan County | 4 | 13.38% | 805 | 710 |
| Douglas County | 5 | 12.61% | 405,741 | 360,315 |
| Ouray County | 6 | 9.8% | 5,357 | 4,879 |
| Archuleta County | 7 | 7.84% | 14,478 | 13,426 |
| Adams County | 8 | 7.62% | 560,079 | 520,411 |
| Broomfield County | 9 | 7.33% | 79,945 | 74,482 |
| Chaffee County | 10 | 7.08% | 20,866 | 19,486 |
| Gilpin County | 11 | 6.43% | 6,191 | 5,817 |
| Dolores County | 12 | 6.39% | 2,480 | 2,331 |
| Grand County | 13 | 6.1% | 16,709 | 15,748 |
| Saguache County | 14 | 5.97% | 6,778 | 6,396 |
| Larimer County | 15 | 5.68% | 380,384 | 359,942 |
| Costilla County | 16 | 5.32% | 3,685 | 3,499 |
| Mesa County | 17 | 5.31% | 164,290 | 156,007 |
| Park County | 18 | 4.9% | 18,279 | 17,425 |
| Morgan County | 19 | 4.18% | 30,296 | 29,080 |
| Bent County | 20 | 3.93% | 5,687 | 5,472 |
| Montrose County | 21 | 3.9% | 44,495 | 42,825 |
| El Paso County | 22 | 3.82% | 761,724 | 733,721 |
| Delta County | 23 | 3.22% | 32,062 | 31,062 |
| Gunnison County | 24 | 3.07% | 17,471 | 16,950 |
| Denver County | 25 | 3.06% | 739,635 | 717,680 |
| Lake County | 26 | 3.02% | 7,633 | 7,409 |
| Huerfano County | 27 | 3% | 7,029 | 6,824 |
| Mineral County | 28 | 2.99% | 896 | 870 |
| Montezuma County | 29 | 2.98% | 26,662 | 25,890 |
| Arapahoe County | 30 | 2.53% | 671,880 | 655,269 |
| Fremont County | 31 | 2.44% | 50,074 | 48,880 |
| Garfield County | 32 | 2.16% | 63,128 | 61,793 |
| La Plata County | 33 | 2.13% | 56,866 | 55,679 |
| Alamosa County | 34 | 1.88% | 16,685 | 16,377 |
| Routt County | 35 | 1.41% | 25,187 | 24,837 |
| Conejos County | 36 | 1.03% | 7,534 | 7,457 |
| Rio Blanco County | 37 | 0.8% | 6,574 | 6,522 |
| Kit Carson County | 38 | 0.69% | 7,111 | 7,062 |
| Summit County | 39 | 0.49% | 31,391 | 31,237 |
| Lincoln County | 40 | 0.39% | 5,688 | 5,666 |
| Teller County | 41 | 0.09% | 24,769 | 24,746 |
| Pueblo County | 42 | 0.03% | 168,392 | 168,334 |
| Crowley County | 43 | -0.02% | 5,706 | 5,707 |
| Jefferson County | 44 | -0.44% | 580,543 | 583,131 |
| Yuma County | 45 | -0.56% | 9,919 | 9,975 |
| Cheyenne County | 46 | -0.69% | 1,734 | 1,746 |
| Boulder County | 47 | -1.01% | 327,635 | 330,982 |
| Prowers County | 48 | -1.23% | 11,864 | 12,012 |
| Las Animas County | 49 | -1.52% | 14,271 | 14,491 |
| Washington County | 50 | -1.95% | 4,716 | 4,810 |
| Kiowa County | 51 | -2.2% | 1,421 | 1,453 |
| Moffat County | 52 | -2.46% | 12,940 | 13,267 |
| Logan County | 53 | -2.84% | 20,618 | 21,221 |
| Eagle County | 54 | -3.07% | 53,947 | 55,657 |
| Phillips County | 55 | -3.14% | 4,386 | 4,528 |
| Clear Creek County | 56 | -4.2% | 8,965 | 9,358 |
| Rio Grande County | 57 | -4.39% | 11,031 | 11,538 |
| San Miguel County | 58 | -4.53% | 7,688 | 8,053 |
| Hinsdale County | 59 | -4.56% | 753 | 789 |
| Baca County | 60 | -4.89% | 3,308 | 3,478 |
| Pitkin County | 61 | -5.06% | 16,484 | 17,363 |
| Otero County | 62 | -6.33% | 17,478 | 18,659 |
| Sedgwick County | 63 | -7.03% | 2,223 | 2,391 |
| Jackson County | 64 | -16.97% | 1,145 | 1,379 |
Colorado's counties show varied growth patterns from 2020 to 2026. Elbert County leads with 3.23% annualized growth, followed by Custer County (2.92%) and Weld County (2.55%). The largest counties are El Paso County (761,724), Denver County (739,635), and Arapahoe County (671,880). Of the 64 counties in Colorado, 42 are growing while 22 have experienced population decline. Overall, counties averaged 0.34% annualized growth, with total population growing by 0.71% annually.
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