The Boulder Timeline was made possible with underwriting support from WK Real Estate, Boulder.




The Fountain Formation was deposited in a series of alluvial fans.  This geologic unit includes the Flatirons, Boulder’s iconic red mountain backdrop.

The Front Range rose, eroded and rose again.

15,000 YEARS AGO
Ice Age glaciation and continuing stream erosion began to give the high peaks and the foothills the shapes they have today.

For thousands of years, the Boulder Valley was home to several tribes of Native Americans.

1600-1800s European colonization forced many Native American tribes further west. The Arapaho and Cheyenne, for example, moved from the Great Lakes Region to the Plains. The nomadic Southern Arapaho, led by Chief Niwot, often wintered in Boulder Valley.


Gold Discovered

Gold was discovered south of Denver, stimulating the Pikes Peak Gold Rush. The first Anglo-European settlers arrived at the mouth of Boulder Canyon, breaching the borders of Arapaho territory as defined by the Fort Laramie Treaty. Chief Niwot granted the group the right to spend the winter and then leave, but the settlers did not honor that agreement to leave.


Gold Triggered Development

Gold was discovered near Gold Hill, west of Boulder, and the Boulder City Town Company was formed on February 10 and Boulder became a supply base for the miners. The town grew to a population of 343 by 1870, with these settlers defying the terms of the Fort Laramie Treaty. The first irrigation ditch in Boulder County was dug, and coal was discovered in the Marshall area southeast of Boulder.


Colorado Territory

Congress voted to create the new Colorado Territory. The admission of new territories was a contentious issue in Congress until the Civil War, which cleared the way for the admission of the free Colorado Territory.


Congregational Church

The Congregational Church began to build and move to 11th and Pine Street, at the site of what is now the Carnegie Library, next door to the Museum of Boulder. The hillside spot was chosen so that the bell tower (the County’s first) would be visible to residents for miles around.



Sand Creek Massacre

Chief Niwot and an estimated 70–500 Native Americans, about two-thirds of whom were women and children, died at the hands of Colorado troops, including officers and men from Boulder, at the Sand Creek Massacre.


Boulder City Incorporated



Colorado became the 38th state on August 1. Known as the Centennial State, it was incorporated 100 years after the signing of the Declaration of Independence.


University of Colorado

The University of Colorado opened on land donated by prominent residents. CU’s first graduating class consisted of men in 1882 and the only building on campus was Old Main. State Preparatory School (later Boulder High) was founded as part of University because of a lack of adequately prepared high school graduates.


Mary Rippon

Mary Rippon was appointed first woman professor at CU, making her the first female to teach at a state university in the country.



Daily Camera Founded

The Boulder Camera was founded to cover local news and became a daily the next year. Still in publication, today it is known as the Daily Camera.


Right to Vote

Women in Colorado won the right to vote, 26 years before the passage of the 19th Amendment, due to a powerful statewide organizing effort in advance of the popular referendum.


100-Year Flood

Sixty straight hours of warm Spring rain combined with a rapid snowmelt to create a 100-year flood that ravaged Boulder. The floodwaters covered most of the town, inundating much of downtown, destroying buildings and bridges. Boulder was split in two as transportation and communication services were knocked out. Reconstruction began soon after the flood but proved an arduous process.



Colorado Sanitarium

The Colorado Sanitarium, a branch of Dr. J.H. Kellogg’s Battle Creek Sanitarium in Michigan, was dedicated in Boulder, originally to combat tuberculosis in Boulder’s dry climate and high altitude.



Switzerland Trail Railroad

The Colorado & Northwestern Railroad route between Boulder and Ward was named “The Switzerland Trail of America”.  It operated until 1919.

Chautauqua Opened

Boulderites approved a $20,000 bond election for the Texas-Chautauqua Auditorium.  Now the Colorado Chautauqua, it hosts lectures, live music, and silent films, and includes the Chautauqua Dining Hall and short-term lodging at the base of the Flatirons. It was designated a National Historic Landmark in 2006.



Foothills Preserved

Boulder’s request for 1,800 acres of mountain backdrop/watershed extending from South Boulder Creek to Sunshine Canyon was approved by Congress.

Tungsten Discovered

Tungsten was discovered in the mountains west of Boulder.  The ore’s value soared, especially when the country’s entry into World War I greatly increased demand. By that time Boulder County was the world’s leading producer of tungsten ore.


Oil Discovered

The Boulder oil field was discovered on what is now the Diagonal Highway near the Airport.  It was the first field in what is now a vast oil & gas producing area, the Denver-Julesburg basin.


Speeding Laws

City ordinance made it “unlawful for any person to ride or drive within Boulder at a rate of speed in excess of 6 miles per hour”.


Carnegie Library

The Carnegie Library was built with money donated by steel tycoon Andrew Carnegie in response to a request from local organizer Clara Savory. Located at 1125 Pine Street, the building was modeled after Greek architecture, reflecting Boulderites’ opinion of their town as the “Athens of the West.” It is now he Carnegie Branch Library for Local History, housing the collections of the Boulder Historical and Genealogical societies.



Anti-Saloon Ordinance

Boulder passed an anti-saloon ordinance, due to a powerful female-led Prohibition Movement. The City did not officially overturn this measure until 1967, although 3.2% beer was legal beginning with the end of Federal Prohibition in 1933.



Ivy Baldwin

Ivy Baldwin made a record-breaking high wire walk on a cable stretched 565 feet high across Eldorado Springs canyon. Now, rock climbers from around the world are drawn to Eldorado Springs, the Flatirons and Boulder Canyon.  Many of the country’s greatest climbers call Boulder home.



Interurban Train

The electric Interurban train made its first run between Boulder and Denver. Its last trip was in 1926. (view of train in Denver)




Boulderado Hotel

The Boulderado Hotel opened for business on New Year’s Day. The city’s first luxury hotel, it is still welcoming guests in an elegant, historic setting.



Miners Strike

3,000 coal miners in Boulder County went on a strike that lasted five years.

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