Boulder County, Colorado
Boulder County: county in Colorado, United States
About
Boulder County is a county located in the U.S. state of Colorado. As of the 2010 census, the population was 294,567 and a population density of 151 people per km². After 10 years in 2020 county had an estimated population of 327,171 inhabitants. Its county seat is Boulder. The county was created 164 years ago in 1861.
County Snapshot
Boulder County at a glance
Boulder County currently has 12 quality-checked populated place pages linked on MapSof, making it easier to jump from the county overview into local city pages.
Mapped populated places
12
These counts use a stricter populated-place filter so the main lists stay focused on real city and town pages.
Colorado counties
64
Open related pagesLargest city
BoulderPopulation 107,645
Top linked places
Quick Facts about Boulder County
| Population | 327,171 (2020) |
| Country | United States of America |
| State | Colorado (United States) |
| Twitter username | bouldercounty |
| Area | 1946 km2 |
| Water as percent of area | 1.9% |
| Land as percent of area | 98.1% |
| Latitude & Longitude | 40.0925,-105.3577 |
| Named for | Boulder Creek, Boulder |
| Altitude | 7,090 feet / 2161 meters |
| Capital | Boulder |
| Establishment | November 01, 1861 |
| Time Zone | America/Denver |
| Local time | 17:29:08 (14th April 2026) |
| Density | 168 Pop. per km² as of 2020 |
| Population growth | 9.97% (2010-2020) |
| Weather | 38℉ Slight Chance Snow Showers 7-days weather |
Geography
Boulder County is located at 40°5'33"N 105°21'28"W (40.0924600, -105.3577000). It has 5 neighbors: Broomfield County, Gilpin County, Jefferson County, Larimer County and Weld County.
Boulder County map
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The largest city of Boulder County is Boulder with a population of 107,645. Other cities include, Longmont population 98,445, Erie population 30,318, Lafayette population 28,579 and Louisville population 19,060. See all Boulder County cities & populated places.
Boulder County Populated Places
Cities, towns, neighborhoods & other populated places in Boulder County.
| City Name | Population | Title |
|---|---|---|
| Boulder | 107,645 | The most populous city in Boulder County, Colorado. |
| Longmont | 98,445 | The most populous city in Boulder County, Colorado. |
| Erie | 30,318 | Town in Boulder County, Colorado, USA |
| Lafayette | 28,579 | City in Colorado |
| Louisville | 19,060 | City in Colorado |
| Superior | 13,413 | Statutory Town in Boulder and Jefferson counties in the U. |
| Niwot | 4,006 | Census designated place |
| Lyons | 2,058 | Town in Boulder County, Colorado, United States |
| Nederland | 1,557 | Town in Colorado, United States |
| Coal Creek | 350 | Town in Fremont County, Colorado, United States |
| Jamestown | 254 | Town in Colorado, USA |
| Ward | 168 | Town in Colorado, United States |
Weather
A slight chance of snow showers. Cloudy, with a low around 38. West wind around 2 mph. Chance of precipitation is 20%.
7-Day ForecastDemographics
The population of Boulder County increased by 9.97% in 10 years.
| Year | Population | % Change | Method |
|---|---|---|---|
| 2010 | 294,567 | - | census |
| 2011 | 299,957 | 1.8% | estimation process |
| 2012 | 304,570 | 1.51% | estimation process |
| 2013 | 309,323 | 1.54% | estimation process |
| 2014 | 312,233 | 0.93% | estimation process |
| 2015 | 318,027 | 1.82% | estimation process |
| 2016 | 321,250 | 1% | estimation process |
| 2017 | 322,441 | 0.37% | estimation process |
| 2018 | 324,636 | 0.68% | estimation process |
| 2019 | 326,196 | 0.48% | estimation process |
| 2020 | 327,171 | 0.3% | estimation process |
Colorado Other Counties (more counties)
| County Name | Population | Title |
|---|---|---|
| Denver | 735,538 | The twentieth most populous city in the United States and the center of the Denver metropolitan area. |
| Denver County | 735,538 | County in Colorado, United States, coterminous with the City of Denver |
| El Paso County | 728,310 | One of the 64 counties in the U. |
| Arapahoe County | 657,452 | County in Colorado, United States |
| Jefferson County | 583,283 | County in Colorado, United States |
| Adams County | 519,883 | County in Colorado, United States |
| Colorado Springs | 482,131 | The second most populous city in Colorado and the center of the Colorado Springs metropolitan area. |
| Aurora | 387,377 | The third most populous city in Colorado and the center of the Denver metropolitan area. |
| Douglas County | 360,750 | County in Colorado, United States |
| Larimer County | 360,428 | County in Colorado, United States |
| Weld County | 333,983 | County in Colorado, United States |
| Pueblo County | 169,823 | County in Colorado, United States |
| Fort Collins | 168,234 | The fifth most populous city in Colorado. |
| Lakewood | 157,429 | The fifth most populous city in Colorado. |
| Mesa County | 155,603 | County in Colorado, United States |
| Thornton | 148,113 | The seventh most populous city in Colorado. |