Population of Counties in Colorado (2021)

The most populous county in Colorado in 2019 is Denver County, home of Denver, with a population of 704,621. This represents significant population growth of 16.81% since the 2010 census. Colorado is home to several other counties exceeding 500,000 residents including El Paso County (699,232), Arapahoe County (643,052), Jefferson County (574,613), and Adams County (503,167). All of these counties have experienced population growth of at least 7% but not exceeding Denver County's growth.

Colorado Counties with Fewest Residents

The smallest county in Colorado in terms of population is San Juan County with just 715 people, up 0.99% from the last census. There are two other counties in Colorado with populations under 800: Mineral County (766) and Hinsdale County (794). Colorado has a total of 26 counties under 10,000 residents. Other small Colorado counties include Kiowa County (1,376), Jackson County (1,385), Cheyenne County (1,845), Dolores County (2,067), and Sedgwick County (2,344). The most significant growth among these counties was Mineral County at 8.81%. Hinsdale County experienced the most dramatic decline with a growth rate of -5.92%.

Colorado Counties with Rapid Growth

Broomsfield County, Colorado experienced the most significant population growth in the state since the census, growing by 21.57%. Other counties with rapid growth rates include Weld County (19.85%), Douglas County (16.85%), Denver County (16.81%), and Larimer County (14.50%). The county that has experienced the most extreme negative growth is Kit Carson County with a growth rate of -13.38% which has brought its population down to 7,158.

Name 2021 Population Growth Since 2010 Density (mi²)
Denver County749,10324.16%1,031.34
El Paso County737,03117.54%1,014.72
Arapahoe County666,17615.91%917.17
Jefferson County589,85910.14%812.10
Adams County529,55519.35%729.07
Larimer County369,37722.94%508.55
Douglas County367,48428.05%505.94
Weld County343,84635.26%473.40
Boulder County329,31611.62%453.39
Pueblo County170,4286.93%234.64
Mesa County156,7287.16%215.78
Broomfield County72,74729.38%100.16
Garfield County60,7818.40%83.68
La Plata County56,0659.05%77.19
Eagle County55,4956.52%76.40
Fremont County47,5991.63%65.53
Montrose County43,8626.50%60.39
Delta County31,7182.78%43.67
Summit County31,39911.85%43.23
Morgan County29,6665.05%40.84
Elbert County27,58119.18%37.97
Montezuma County26,2452.62%36.13
Teller County25,93810.52%35.71
Routt County25,90010.52%35.66
Logan County22,691-0.26%31.24
Chaffee County20,98617.85%28.89
Park County19,48519.69%26.83
Otero County18,158-3.72%25.00
Gunnison County18,05218.06%24.85
Pitkin County17,3491.14%23.89
Alamosa County16,2034.43%22.31
Grand County16,1809.35%22.28
Archuleta County14,62721.43%20.14
Las Animas County14,502-5.97%19.97
Moffat County13,483-2.25%18.56
Prowers County12,358-1.49%17.01
Rio Grande County11,259-6.35%15.50
Yuma County10,1631.13%13.99
Clear Creek County9,8928.91%13.62
Lake County8,68919.62%11.96
Conejos County8,253-0.71%11.36
San Miguel County8,17711.15%11.26
Kit Carson County6,973-15.61%9.60
Huerfano County6,9173.53%9.52
Saguache County6,79210.69%9.35
Gilpin County6,50518.90%8.96
Rio Blanco County6,312-4.70%8.69
Crowley County6,2696.96%8.63
Lincoln County5,8917.68%8.11
Custer County5,33624.70%7.35
Ouray County5,21216.97%7.18
Bent County5,115-21.31%7.04
Washington County4,9482.63%6.81
Phillips County4,225-5.46%5.82
Costilla County4,03714.40%5.56
Baca County3,575-6.09%4.92
Sedgwick County2,192-7.55%3.02
Dolores County2,045-1.16%2.82
Cheyenne County1,775-3.16%2.44
Kiowa County1,4603.99%2.01
Jackson County1,386-0.22%1.91
Hinsdale County8440.00%1.16
Mineral County7638.38%1.05
San Juan County656-7.34%0.90