Community Description

Jefferson County, named after the third U.S. President Thomas Jefferson, was formally organized by the Colorado Territorial Legislature in 1861. Though it has roots as an agricultural and mining community, the county is now the fourth most populous in the state of Colorado (1,2). Known as the “Gateway to the Rockies,” Jefferson County is located just west of Denver (3). The county spans 773 square miles and houses approximately 574,000 residents (1,3). The county is geographically diverse, with about 72 percent of the land located in the western Rocky Mountain region, and the foothills and plains making up the remaining eastern portion (2,3).

The county includes both urban and rural areas, including seven cities, five towns, 14 census-designated places and six unincorporated areas.

For more background on Jefferson County, including leadership, departments and offices, public services, maps and more, visit the county website


Demographics

2017 Jefferson County Population Estimates

574,613 residents
  • 50.1% female (50.3% CO)
  • 49.9% male (49.7% CO)
  • 6,803 live births
  • 4,550 deaths


Race/Ethnicity
  • 78.3% non-Hispanic White (68.3% CO)
  • 15.4% Hispanic, all races (21.5% CO)
  • 1.1% non-Hispanic Black (4.0% CO)
  • 2.8% non-Hispanic Asian (3.2% CO)
  • 2.4% non-Hispanic other or multi-racial (3.0% CO)

Age distribution:
  • Median age: 40.4 years (36.8 years CO)
  • 114,968 younger than age 18
  • 367,409 ages 18-to-64
  • 92,236 age 65 and older

Percent of Jefferson County's Population by Age Group, and compared to Colorado overall

Source: US Census: 2017 Annual Population Estimates, Table: PEPAGESEX

The maps below show the distribution of Jefferson County's population by age group by census tract (2013-2017). Darker colors represent higher percentages of the population in that age group.

Percent under 18 years of age

Percent 18 to 64 years of age

Percent 65 years of age and over

Source: U.S. Census - ACS 2013-2017, 5 year estimates, Table: S0101

Population Distribution and Trends

The maps below show both the total population in each census tract in Jefferson county and the number of people per square mile. Darker areas represent more people or greater density.

Total population by census tract (2013-2017)

Persons per square mile, by census tract (2013-2017)

Source: U.S. Census - ACS 2013-2017, 5 year estimates, Table: S0101

Minority and Foreign-Born Populations

Percent of the population that are people of color, by census tract

Percent of the population who are foreign born, by census tract

Source: U.S. Census - ACS 2013-2017 5-year estimates, Tables: B03002 & B05002

Languages Spoken

In Jefferson County, 10.9 percent of the population (over the age of five) speaks another language other than English. Overall, 3.4 percent (~17,551 residents) of our population speaks English less than very well (Colorado = 6.0 percent and United States = 8.5 percent).

- U.S. Census, American Community Survey 5-year estimates (2013-2017) data, Table: S1601

Percent of the population that speaks selected languages (among those over the age of five), Jefferson County, Colorado, and United States (2013-2017) 

Source: U.S. Census - ACS 2013-2017 5-year estimates, Table: C160001

Source: U.S. Census - ACS 2013-2017 5-year estimates, Table: S1601

Below are the percentages of those who speak English less than very well, among those who who speak that language primarily.

Source: U.S. Census - ACS 2013-2017 5-year estimates, Table: C160001

Percent of the population who speak English less than very well, by census tract

Source: U.S. Census - ACS 2013-2017 5-year estimates, Table: S1601

Geographic Mobility

In the last year, of those living below poverty, 10.2 percent moved from one location to another within Jefferson County, compared to 6.0 percent of those living above the poverty level. In addition, 5.4 percent of those living below poverty moved from another county in Colorado to Jefferson County, compared to 4.3 percent of those living above the poverty level. 

- U.S. Census - American Community Survey, 2017 1-year estimate

Relocation within and to Jefferson County within the past year (2017)

Source: U.S. Census - ACS 2017 1-year estimate, Table: S0701

Those living in rental housing were more likely to have moved in the last year (28.3 percent vs 9.6 percent) than those living in owned housing.

- U.S. Census - American Community Survey, 2017 1-year estimate, Table S0701

Geographic mobility, percent of the population that has moved into Jefferson County in the last year, by census tract

Source: U.S. Census - ACS 2013-2017 5-year estimates, Table: S0701

Families and Marital Status

Note: The U.S. Census currently designates all same sex unions as unmarried, regardless of legal status. Their definition is set to change with the 2020 Decennial Census.

Lesbian, Gay, Bisexual, Transgender (LGBT) Data and Demographics

Colorado's population is made up of 3.9 percent of persons identifying as either lesbian, gay, bisexual or transgender. Demographic information is described below.

Source: The Williams Institute, UCLA School of Law: Same-sex Couple and LGBT Demographic Data Interactive

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Reference List

1. Jefferson County. (2018). Life in JeffCo. Retrieved from: https://www.jeffco.us/2574/Life-in-Jeffco

2. United States Census Bureau. (2018). American Fact Finder. Retrieved from: https://factfinder.census.gov/faces/nav/jsf/pages/index.xhtml

3. Jefferson County. (2017). Community Profile for 2017. Retrieved from: https://www.jeffco.us/DocumentCenter/View/2371/Community-Profile-PDF 

Data Sources

U.S. Census, Annual Population Estimates - American Factfinder (Tables: PEPANNRES, PEPAGESEX, PEPSR6H): https://www.census.gov

U.S. Census, ACS: American Community Survey - American Factfinder (Tables S1601, C160001, S0701, S1201, S1101): https://www.census.gov

CDPHE Vital Records: Colorado Department of Public Health and Environment: http://www.chd.dphe.state.co.us/cohid/Default.aspx

Colorado State Demography Office, Components of Change by County:  https://demography.dola.colorado.gov/data/

The Williams Institute, UCLA School of Law: Same-sex Couple and LGBT Demographic Data Interactive: https://williamsinstitute.law.ucla.edu/visualization/lgbt-stats

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Published on July 17, 2018

Updated on June 21, 2019