Colorado

Boulder

330,758

2020 population

1870

first census record

census records

About Boulder

Boulder, Colorado, first appears in the United States federal census in 1870, when it recorded a population of 1,939. At the most recent census, in 2020, its population stood at 330,758.

The county's recorded population has risen across the decades to its highest level in 2020.

On the ground today, 95 places are listed on the National Register of Historic Places.

Population by decade

Census Year	Population	Chart
2020	330,758
2010	294,567
2000	291,288
1990	225,339
1980	189,625
1970	131,889
1960	74,254
1950	48,296
1940	37,438
1930	32,456
1920	31,861
1910	30,330
1900	21,544
1890	14,082
1880	9,723
1870	1,939

Source

Population data from the United States decennial census, U.S. Census Bureau (public domain).

Historic places in Boulder

National Register of Historic Places listings in Boulder, Colorado.

Lafayette House

Lafayette

St. Stephen's Episcopal Church, 1881

Longmont

Thunder Lake Trail-Bluebird Lake Trail

Allens Park

First Congregational Church of Lyons

Callahan, T. M., House

Longmont

Ward Congregational Church

Ward

Lewis House

Lafayette

Wall Street Assay Office

Wallstreet

Hoverhome and Hover Farmstead

Longmont

Thunder Lake Patrol Cabin

Estes Park

Highland School

Boulder

North St. Vrain Creek Bridge

Chautauqua Auditorium

Boulder

Salina School

Salina

Wild Basin Ranger Station and House

Estes Park

Downtown Boulder Historic District

Boulder

Denver, Boulder and Western Railway Historic District

Ward

Browse all Coloradohistoric sites ›

Other counties in Colorado

Explore census history and historic records for more Colorado counties.

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Everything a full report reveals about Boulder County, Colorado

This page charts the census history of Boulder County, Colorado. A full Aubrey report for an address here pulls together everything the historical record holds about the ground, from the earliest settlement to the twentieth century:

Overview

An interactive map of the location with historic sites, battles and Native heritage plotted, and its full story era by era.

The Land

The historic sites and place names around the location, and how this land was settled and used.

Geology

The bedrock beneath the site, its age and rock type, reaching back millions of years.

LiDAR Terrain

Laser-scanned terrain that reveals earthworks and old features hidden in the landscape.

Conflict & War

The battles, raids and skirmishes fought near here, across every era of American conflict.

The Civil War

The Civil War on this ground, 1861 to 1865: who held it, and the battles, camps and regiments nearby.

The Soldiers

The men who marched from here in the Civil War, named and traced where the record allows.

Native Heritage

The Native nations who held this land, mapped across time from before European contact to today.

Settlement

Who claimed and held this ground, from Indigenous homelands through the colonial powers to the United States.

The Community

How the town grew, who came, and what kind of place it became, traced through the census record.

Rivers & Rail

The rivers, canals and railroads that connected this place between 1830 and 1911.

Notable People

The people born, buried or genuinely tied to this exact place, with their stories.

Historical Maps

Historic maps of the location layered over how it looks today.

Finds & Access

Museum objects tied to the area, and the laws on searching, collecting and access here.

Literature

The old books, county histories and archives that mention this place, quoted with their sources.

Spotlight

A deep dive into the most remarkable, lesser-known history of the place, traced back to the record.

Points of Interest

The most significant historic sites and landmarks near the location, and why they matter.

Timeline

The whole story of the location told era by era, from first peoples to the present day.

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Coloradohistory ›NRHP historic sites ›Notable people from Colorado›

Frequently asked about Boulder

When does Boulder first appear in the US census?

Boulder, Colorado first appears in the federal census in 1870, with a recorded population of 1,939.

What is the population of Boulder?

At the most recent federal census (2020), Boulder had a recorded population of 330,758.

How many historic places are in Boulder?

95 sites are listed on the National Register of Historic Places in Boulder, Colorado.

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