Colorado State Senate District 18

State Legislative District Profile (Upper Chamber)

Overview

District ID
co-sd-018
State
Colorado
Chamber
Upper chamber (state senate)
District Code
018
Land Area
78.7 sq mi
Water Area
3.64 sq mi

Boundary

Boundary of Colorado State Senate District 18

Boundary as GeoJSON

Source: U.S. Census Bureau TIGER/Line state legislative district boundaries.

Counties

CountyOverlapShare of district landShare of county land
Boulder County78.64 sq mi100.0%10.8%

Showing all 1 county

Places

PlaceOverlapShare of district landShare of place land
Boulder city26.33 sq mi33.5%98.0%
Louisville city7.96 sq mi10.1%99.9%
Gunbarrel CDP6.25 sq mi7.9%100.0%
Niwot CDP4.00 sq mi5.1%100.0%
Superior town3.73 sq mi4.7%94.8%
Paragon Estates CDP1.68 sq mi2.1%100.0%
Valmont CDP0.27 sq mi0.3%100.0%

Showing all 7 places

Overlapping Congressional Districts

Congressional districtPopulation in bothShare of this district's populationShare of the congressional district's populationShare of this district's land
CO District 2164,205100.0%22.8%100.0%

Source: U.S. Census Bureau 2020 blocks and 2025 block equivalency files (119th Congress, 2024 state legislative plans).

Voters

Registered Voters
120,668
Active Voters
105,178 (87.2%)

Party Registration

PartyVotersShare
Democratic51,08042.3%
Republican8,3276.9%
Unaffiliated58,98448.9%
Other parties2,2771.9%
No party recorded00.0%

Turnout by Cycle

CycleGeneralDemocratic PrimaryRepublican Primary
2025–202657,492 (47.6%)0 (0.0%)0 (0.0%)
2023–202493,200 (77.2%)25,747 (21.3%)4,151 (3.4%)
2021–202275,290 (62.4%)20,396 (16.9%)2,972 (2.5%)
2019–202078,909 (65.4%)34,530 (28.6%)4,325 (3.6%)
2017–201863,806 (52.9%)22,027 (18.3%)3,007 (2.5%)
2015–201661,434 (50.9%)11,199 (9.3%)2,595 (2.2%)
2013–201447,892 (39.7%)9,051 (7.5%)2,897 (2.4%)
2011–201250,680 (42.0%)9,147 (7.6%)2,417 (2.0%)

Turnout counts today's registered voters with a counted ballot in the cycle's elections (the odd and even year), as a share of today's registered voters. Voters who have since left the rolls are not counted.

Browse the voter list for this district (premium access; sign-in required)

Source: Civitech voter file snapshot as of 01/20/2026. These are registered voters, separate from the Census population figures. Counts under 10 are suppressed and shown as "<10".

Demographics

Total Population
160,886 (± 1,003)
Median Age
32.8
Median Household Income
$105,382 (± $4,856)
High School Graduate or Higher (age 25+)
97.9%
Bachelor's Degree or Higher (age 25+)
75.0%

Population by Age

GroupPeopleShare
Under 1824,21715.1%
18 to 64113,68970.7%
65 and over22,98014.3%

Population by Race and Hispanic Origin

GroupPeopleShare
Hispanic or Latino (any race)16,10010.0%
White, not Hispanic125,43178.0%
Black, not Hispanic1,4180.9%
Asian, not Hispanic9,2855.8%
American Indian / Alaska Native, not Hispanic2660.2%
Native Hawaiian / Pacific Islander, not Hispanic520.0%
Some other race, not Hispanic5700.4%
Two or more races, not Hispanic7,7644.8%

Source: U.S. Census Bureau, American Community Survey 2020-2024 ACS 5-year estimates (tables B01001, B01002, B01003, B03002, B15003, B19013) for this state legislative district. Estimates are survey-based; ± figures are 90% margins of error.

Citizen Voting Age Population

Total Citizen Population
152,569
Citizen Voting Age Population (CVAP)
128,825

Citizen Population by Race/Ethnicity

GroupCitizensShare
Non-Hispanic138,04690.5%
Hispanic14,5259.5%
White124,80681.8%
Black1,3680.9%
Asian6,2764.1%
American Indian / Alaska Native2590.2%
Native Hawaiian / Pacific Islander510.0%
Two or More Races2650.2%

Citizen Voting Age Population by Race/Ethnicity

GroupCVAPShare
Non-Hispanic117,85791.5%
Hispanic10,9658.5%
White107,30983.3%
Black2,0321.6%
Asian7,3675.7%
American Indian / Alaska Native8760.7%
Native Hawaiian / Pacific Islander530.0%
Two or More Races2170.2%

Source: Redistricting Data Hub / U.S. Census Bureau CVAP Special Tabulation (2020-2024 ACS 5-year).