Jefferson County, Colorado Population 2026
Updated April 2026 · US Census ACS 2023 5-Year Estimates · 4th-largest in Colorado
The population of Jefferson County, Colorado is 579,715 as of the 2023 American Community Survey, making it the 4th-largest county in Colorado. The median household income is $107,800, the median home value is $604,400, and the median age is 40.4.
The population of Jefferson County has grown 8.0% since 2010 (535,567 → 578,533), a +0.55% annualized rate.
579,715
Population
+0.55%
Annual growth
758
People / sq mi
$107,800
Median Income
$604,400
Median Home Value
Jefferson County covers 764 sq mi of land at 758.4 people per square mile.
About Jefferson County, CO
Jefferson County is a county in Colorado with a population of 579,715. It ranks #4 among counties in Colorado by population. The median age is 40.4, older than the national median. The population is 50.3% male and 49.7% female.
The median household income in Jefferson County is $107,800, above the US median of $74,580. 3.7% of residents live below the federal poverty level. Home values sit at a median of $604,400, with monthly rent averaging $1,792. The homeownership rate of 70.6% is higher than the national rate of 64.8%.
Educational attainment in Jefferson County reflects 50.7% of adults 25 and older holding a bachelor's degree or higher, above the national average of 34.3%. Roughly 22.3% of workers primarily work from home, noticeably above the national work-from-home rate of 14.2%. The average commute is 26.6 minutes each way.
Jefferson County Population History (2010-2024)
The county of Jefferson County had a population of 535,567 in 2010 and 578,533 in 2024, a 8.0% growth over 14 years. The peak was 583,169 in 2020. Average annual growth rate: 0.55%.
578,533
Population (2024)
535,567
Population (2010)
583,169
Peak (2020)
0.55%
Avg Annual Growth
| Year | Population |
|---|---|
| 2010 | 535,567 |
| 2011 | 540,582 |
| 2012 | 546,736 |
| 2013 | 552,242 |
| 2014 | 559,099 |
| 2015 | 565,240 |
| 2016 | 571,823 |
| 2017 | 576,041 |
| 2018 | 580,027 |
| 2019 | 582,800 |
| 2020 | 583,169 |
| 2021 | 580,854 |
| 2022 | 576,635 |
| 2023 | 577,693 |
| 2024 | 578,533 |
Race & Ethnicity
| White | 82.0% |
| Black or African American | 1.1% |
| Asian | 0.1% |
| Hispanic or Latino (any race) | 2.3% |
| Two or More Races | 0.0% |
Age & Sex
40.4
Median Age
49.7%
Female
50.3%
Male
17.5%
Age 65+
Age Distribution
Children (under 15): 15.4% · Seniors (65+): 17.5%
Income & Poverty
| Median household income | $107,800+$15,330 vs state |
| Mean household income | $137,752 |
| Per-capita income | $58,142 |
| Poverty rate | 3.7%-2.2% vs state |
| Unemployment rate | 2.7% |
| Employment-to-population | 66.6% |
Top Industries by Employment
The largest employment sector in Jefferson County is professional & business services, accounting for 20.3% of workers.
How residents commute
1.7%
Drive alone
1.4%
Carpool
67.0%
Public transit
22.3%
Work from home
26.6 min
Avg commute
Housing
$604,400+$102,200 vs state
Median home value
$1,792
Median rent
70.6%
Homeownership rate
251,183
Total housing units
95.6%
Occupied
4.4%
Vacant
29.4%
Renter-occupied
Social & access
94.8%
With health insurance
97.2%
With broadband internet
47.2%
Foreign-born
6.8%
Veterans (18+)
10.8%
With a disability
90.1%
Speak language other than English at home
Education
95.5%
High School+
50.7%
Bachelor's+
Largest cities in Colorado
Other counties in Colorado
Part of Colorado
Metro areas in Colorado
County rankings
Common questions about Jefferson County, CO
Frequently Asked Questions
Jefferson County, Colorado has a population of 579,715 according to the US Census Bureau's 2023 American Community Survey 5-year estimates, making it the 4th-largest county in Colorado. Population density is 758 people per square mile.
The population of Jefferson County has grown 8.0% since 2010 (535,567 → 578,533), a +0.55% annualized rate.
The median household income in Jefferson County, Colorado is $107,800, with mean (average) household income of $137,752 and per-capita income of $58,142. 3.7% of residents live below the federal poverty level.
In Jefferson County, the largest racial and ethnic groups are White (82.0%), Hispanic or Latino (2.3%), Black or African American (1.1%). Figures are from the US Census Bureau's 2023 ACS 5-year estimates and reflect self-reported responses.
The median age in Jefferson County, Colorado is 40.4 years. Residents are 49.7% female and 50.3% male.
The median home value in Jefferson County is $604,400 and median monthly rent is $1,792. 70.6% of occupied housing units are owner-occupied. The county has 251,183 total housing units, 4.4% of which are vacant.
The largest employment sector in Jefferson County, Colorado is professional, scientific, and management services, employing 20.3% of workers. The unemployment rate is 2.7%.
Denver is among the largest cities associated with Jefferson County, Colorado, with a population of 713,734.
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Statewide data for Colorado
Population, race, income, age, and trends across Colorado
Data from the American Community Survey (ACS) 5-Year estimates.
Source: U.S. Census Bureau ACS, 2026.