Boulder County , Colorado

Boulder County: County in Colorado, United States

Boulder County locator map
Location of Boulder County on Colorado map.


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 9 years in 2019 county had an estimated population of 326,196 inhabitants. Its county seat is Boulder. The county was created 159 years ago in 1861.


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 Courthouse '31861249120' image
Boulder County Courthouse '31861249120'

The largest city of Boulder County is Boulder with a population of 105,673. Other cities include, Longmont population 97,261, Lafayette population 30,687, Louisville population 20,816 and Pine Brook Hill population 983. See all Boulder County cities & populated places.


Boulder County forecast: A chance of showers and thunderstorms before midnight. Mostly cloudy, with a low around 63. more

Boulder County Courthouse '31861249120' image

Boulder County map

Boulder County Quick Facts

Population : 326,196 (2019)
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%
Named for : Boulder Creek, Boulder
Altitude : 7,090 feet / 2161 meters
Capital : Boulder
Establishment : November 11, 1861
Time Zone : America/Denver
Local time : 02:17:29 (3rd August 2021)
Density : 168 Pop. per km² as of 2019
Population growth : 9.7% (2010-2019)
Weather : 63℉ Chance Showers And Thunderstorms then Mostly Cloudy 7-days weather

Boulder County has 5 neighbours.


The population of Boulder County increased by 9.7% in 9 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

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Boulder County Populated Places (more)

Cities, Towns, Neighborhoods & Other Populated Places in Boulder County.

City Name Population Title
Boulder 105,673 City in Colorado, United States of America
Longmont 97,261 City in Colorado, USA
Lafayette 30,687 City in Colorado
Erie 27,003 Town in Boulder County, Colorado, USA
Louisville 20,816 City in Colorado
Superior 13,087 Statutory Town in Boulder and Jefferson counties in the U.
Niwot 4,006 Census designated place
Lyons 2,189 Town in Boulder County, Colorado, United States
Nederland 1,533 Town in Colorado, United States
Pine Brook Hill 983
Paragon Estates 928
Lazy Acres 920
Eldorado Springs 585
Allenspark 528
Altona 501
Coal Creek 350 Town in Fremont County, Colorado, United States

Colorado Other Counties (more counties)

County Name Population Title
Colorado 5,758,736 State of the United States of America
Denver 727,211 Capital city of the state of Colorado, United States; consolidated city and county
Denver County 727,211 County in Colorado, United States, coterminous with the City of Denver
El Paso County 720,403 One of the 64 counties in the U.
Arapahoe County 656,590 County in Colorado, United States
Jefferson County 582,881 County in Colorado, United States
Adams County 517,421 County in Colorado, United States
Colorado Springs 478,221 County seat of El Paso County, Colorado, United States
Aurora 379,289 City in Kane County, Illinois, United States
Larimer County 356,899 County in Colorado, United States
Douglas County 351,154 County in Colorado, United States
Weld County 324,492 County in Colorado, United States
Fort Collins 170,243 Municipality and county seat of Larimer County, Colorado, United States
Pueblo County 168,424 County in Colorado, United States
Lakewood 157,935 City in Colorado
Mesa County 154,210 County in Colorado, United States

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