| Rank |
County |
Population (2012) |
| 1 |
El Paso County, Colorado
|
644,964
|
| 2 |
Denver County, Colorado
|
634,265
|
| 3 |
Arapahoe County, Colorado
|
595,546
|
| 4 |
Jefferson County, Colorado
|
545,358
|
| 5 |
Adams County, Colorado
|
459,598
|
| 6 |
Larimer County, Colorado
|
310,487
|
| 7 |
Boulder County, Colorado
|
305,318
|
| 8 |
Douglas County, Colorado
|
298,215
|
| 9 |
Weld County, Colorado
|
263,691
|
| 10 |
Pueblo County, Colorado
|
160,852
|
| 11 |
Mesa County, Colorado
|
147,848
|
| 12 |
Broomfield County, Colorado
|
58,298
|
| 13 |
Garfield County, Colorado
|
56,953
|
| 14 |
La Plata County, Colorado
|
52,401
|
| 15 |
Eagle County, Colorado
|
51,874
|
| 16 |
Fremont County, Colorado
|
46,788
|
| 17 |
Montrose County, Colorado
|
40,725
|
| 18 |
Delta County, Colorado
|
30,432
|
| 19 |
Morgan County, Colorado
|
28,472
|
| 20 |
Summit County, Colorado
|
28,044
|
| 21 |
Montezuma County, Colorado
|
25,431
|
| 22 |
Teller County, Colorado
|
23,389
|
| 23 |
Elbert County, Colorado
|
23,383
|
| 24 |
Routt County, Colorado
|
23,334
|
| 25 |
Logan County, Colorado
|
22,631
|
| 26 |
Otero County, Colorado
|
18,698
|
| 27 |
Chaffee County, Colorado
|
18,150
|
| 28 |
Pitkin County, Colorado
|
17,263
|
| 29 |
Alamosa County, Colorado
|
16,148
|
| 30 |
Park County, Colorado
|
16,029
|
| 31 |
Gunnison County, Colorado
|
15,475
|
| 32 |
Las Animas County, Colorado
|
14,945
|
| 33 |
Grand County, Colorado
|
14,195
|
| 34 |
Moffat County, Colorado
|
13,200
|
| 35 |
Prowers County, Colorado
|
12,389
|
| 36 |
Archuleta County, Colorado
|
12,070
|
| 37 |
Rio Grande County, Colorado
|
11,943
|
| 38 |
Yuma County, Colorado
|
10,119
|
| 39 |
Clear Creek County, Colorado
|
9,026
|
| 40 |
Conejos County, Colorado
|
8,275
|
| 41 |
Kit Carson County, Colorado
|
8,094
|
| 42 |
San Miguel County, Colorado
|
7,580
|
| 43 |
Lake County, Colorado
|
7,338
|
| 44 |
Rio Blanco County, Colorado
|
6,857
|
| 45 |
Huerfano County, Colorado
|
6,596
|
| 46 |
Saguache County, Colorado
|
6,304
|
| 47 |
Bent County, Colorado
|
5,773
|
| 48 |
Gilpin County, Colorado
|
5,491
|
| 49 |
Lincoln County, Colorado
|
5,453
|
| 50 |
Crowley County, Colorado
|
5,365
|
| 51 |
Washington County, Colorado
|
4,766
|
| 52 |
Ouray County, Colorado
|
4,530
|
| 53 |
Phillips County, Colorado
|
4,367
|
| 54 |
Custer County, Colorado
|
4,249
|
| 55 |
Baca County, Colorado
|
3,751
|
| 56 |
Costilla County, Colorado
|
3,594
|
| 57 |
Sedgwick County, Colorado
|
2,383
|
| 58 |
Dolores County, Colorado
|
1,994
|
| 59 |
Cheyenne County, Colorado
|
1,874
|
| 60 |
Kiowa County, Colorado
|
1,444
|
| 61 |
Jackson County, Colorado
|
1,348
|
| 62 |
Hinsdale County, Colorado
|
810
|
| 63 |
Mineral County, Colorado
|
709
|
| 64 |
San Juan County, Colorado
|
690
|