How many people live in Adams County, CO?
Updated Apr. 6, 2026Refreshed annually
In 2024, there were about 543,000 people living in Adams County, CO. That makes Adams County the fifth-most populous county in Colorado. It is home to 9% of people living in the state.
543K
population of Adams County, CO (2024)
9%
County share of the Colorado population (2024)
About 543,000 people lived in Adams County, CO in 2024.
Population estimates, 2000–2024
What are Adams County, CO’s age demographics?
About 64,300 Adams County, CO residents are aged 65 and older in 2024. That represents 11.8% of its population. For comparison, the age group represents 16.5% of Colorado’s population and 18% in the US overall.
Another 129,700 Adams County residents, or 23.9% of the population, were children under 18. For comparison, the age group represents 20.5% of Colorado’s population and 21.6% in the US overall.
A lower share of Adams County, CO's population is aged 65 or older than the US as a whole.
Population estimates by age group, (2024)
What are Adams County, CO’s racial and ethnic demographics?
Hispanic residents make up 43.7% of the Adams County, CO population, higher than the national share of 20%.
In contrast, Adams County’s non-Hispanic white population accounts for 44.6%, below the 57.5% nationwide, and the non-Hispanic Black or African American population makes up 3.9% of the county, compared with 12.6% nationally.
Racial and ethnic make up differ based on location. These figures reflect how people identified their race alone (not in combination with other races), and separate out Hispanic or Latino ethnicity, following Census reporting standards.
Adams County, CO has a higher share of a Hispanic population than Colorado as a whole.
Population estimates by race and ethnicity, (2024)
The largest city or town in Adams County, CO is Thornton with about 146,700 residents in 2024.
Cities and towns in Adams County, CO ranked by population
Population (2024), includes only portions within county
| City or town | Population | |
|---|---|---|
| 1. | Thornton (pt.) | 146,689 |
| 2. | Commerce City | 70,245 |
| 3. | Westminster (pt.) | 69,508 |
| 4. | Aurora (pt.) | 57,648 |
| 5. | Brighton (pt.) | 43,014 |
| 6. | Northglenn (pt.) | 38,262 |
| 7. | Federal Heights | 13,971 |
| 8. | Bennett (pt.) | 3,482 |
| 9. | Arvada (pt.) | 2,781 |
| 10. | Lochbuie (pt.) |
Keep exploring
Methodology
USAFacts standardizes data, in areas such as time and demographics, to make it easier to understand and compare.
The analysis was generated with the help of AI and reviewed by USAFacts for accuracy.
Page sources
USAFacts endeavors to share the most up-to-date information available. We sourced the data on this page directly from government agencies; however, the intervals at which agencies publish updated data vary.
