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
Remote work is unusually prominent in Jefferson County: 22.3% of workers primarily work from home, above the 14.0% national rate. Jefferson County is a county in Colorado with a population of 579,715. That makes it one of the ten largest counties in Colorado in the country, at #4 by population.
Households here are among the highest-earning of all US counties: median income is $107,800, above the US median of $78,538. Poverty is among the lowest of comparable US counties, at 3.7% — below the national 12.4%. Real estate commands a premium here — a median home value of $604,400, with typical rent around $1,792.
The population is unusually well-credentialed for US counties — 50.7% of adults have a four-year degree, above the national 35.0%. An unusually large 22.3% of workers are remote, above the national 14.0%, and the average commute runs about 27 minutes each way.
The remote-work concentration is telling in Jefferson County — it skews toward higher-income, college-educated workers and reshapes both commute patterns and housing demand.
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
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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.
Jefferson County, CO Climate
Jefferson County, CO has an average annual temperature of 6.1°C (43°F) and receives about 462 mm of precipitation per year. The warmest month is July and the coldest is January. Figures are 1970–2000 climate normals.
6.1°C
Avg Temp
462
Precip (mm/yr)
Jul
Hottest Month
Jan
Coldest Month
| Month | Avg (°C/°F) | Precip |
|---|---|---|
| January | -3° / 27° | 12 mm |
| February | -2° / 28° | 17 mm |
| March | 1° / 33° | 37 mm |
| April | 4° / 39° | 50 mm |
| May | 9° / 48° | 61 mm |
| June | 14° / 57° | 51 mm |
| July | 17° / 63° | 64 mm |
| August | 16° / 62° | 60 mm |
| September | 12° / 54° | 37 mm |
| October | 7° / 44° | 31 mm |
| November | 1° / 33° | 23 mm |
| December | -3° / 27° | 19 mm |
1970–2000 normals from WorldClim 2.1 (~9 km grid). Precipitation can be less precise near mountains or coastlines, where rainfall varies sharply over short distances.
Best time to visit Jefferson County, CO
The most comfortable months to visit Jefferson County, CO are typically July, August and June, when temperatures are mildest and rainfall is relatively low. The hottest month is July (around 26°C high). The coldest is January (near -11°C low). July is usually the wettest month.
Where to stay near Jefferson County
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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.