Longmont History


Access our online history brochure here!

Cover Photo: Longmont Museum & Cultural Center Historical Archives

Indigenous peoples have traveled through and lived in the area where Longmont is today for thousands of years. Perhaps the best-known early group, the Clovis people, lived in northern Colorado at least 14,000 years ago. A succession of other peoples moved through Colorado, including the Folsom people around 13,000 years ago and the Plano people around 11,000 years ago. The dry climate, however, made continuous habitation difficult, and archaeological evidence indicates the northern plains were unoccupied for centuries.

The Cheyenne, Lakota, Arapaho, Kiowa, and Comanche all followed huge buffalo herds across the American Plains, spending time in Colorado yearly. European explorers began encountering these tribes in what is now Colorado in the 1500s.

One of the first American explorers to reach the Longmont area was Major Stephen H. Long. The most prominent mountain in northern Colorado, Longs Peak, was named for Major Long, who reached the edge of the St. Vrain valley in 1820.

Although the Cheyenne and Arapaho had signed treaties with the U.S. government guaranteeing their right to the land, the discovery of gold in Colorado in 1858 led to a rush of miners and speculators. The miners disregarded treaty rights and set off a conflict that ended in 1868 with the military removal of Cheyenne and Arapaho peoples to reservations in Wyoming and Oklahoma.

The railroad arrived in Denver in 1870, cutting weeks off the journey from cities in the east. This led to the formation of Longmont, which began unusually. In 1870, a group of prominent men in Chicago decided to start a new town in Colorado. They sold memberships in this new town called the "Chicago-Colorado Colony." The money raised paid for thousands of acres of land for a town site and nearby farms. They planned the city and brought the people, lumber and building materials to the barren site. By the summer of 1871, they had built a small town named "Longmont" in honor of Longs Peak, the tallest nearby mountain.

The Colony planners designed Longmont to look like many other towns in America. The original one-square-mile plan had stores along Main Street, homes arranged in a grid spreading out from Main Street and three parks in different areas of town.

While the climate of Longmont is dry, the soil is rich and, with water provided, will produce excellent crops. Irrigation canals, built by local farmers and later by larger organizations, ensured a steady water supply for the fields. As the town grew, large-scale agricultural industries arrived, first flour mills in 1872, then the Empson vegetable cannery in 1889. The construction of a sugar factory in 1903 on the east edge of town provided another critical industry, soon called the Great Western Sugar Co. With enough labor to tend them, sugar beets grew well in northeastern Colorado because of the availability of irrigation water.

The need for labor in the sugar beet fields attracted many people. People came from Sweden, Norway, and Denmark and settled northwest of Longmont. Russian-Germans arrived in the early 1900s. Latinos arrived from New Mexico, Texas, and Mexico. People came from Japan and moved from sugar beets to vegetable farming. All these groups remain an essential part of Longmont's heritage, and their descendants still live in and around Longmont.

By 1910, the population of Longmont had doubled just about every ten years since its founding. It now had 4,256 residents. Growth slowed after this, with 5,848 people recorded in the 1920 census. World War I took its toll on Longmont's young men, and the flagpole that stands today in Roosevelt Park records the names of those who died in service.

In 1925, the Ku Klux Klan gained control of Longmont's City Council in an election. They began constructing a large pork-barrel project, Chimney Rock Dam, above Lyons and marched up and down Main Street in costumes. Their influence soon declined when voters removed them from office In the 1927 election. Work on Chimney Rock Dam was abandoned as unfeasible, although its foundations are still visible in the St. Vrain River.

The Great Depression, which lasted from 1929 to 1939, affected the whole world, including Longmont. Prolonged drought during the 1930s dried out the soil of the Great Plains. Windstorms picked up vast quantities of dust, and black dust clouds towered over Longmont. The drought eased by the late 1930s, and the economy improved. Only the United States' entry into World War II in 1941 finally ended the Great Depression in this country.

More than 2,000 people from Longmont fought in World War II. Women worked in factories and offices instead of men who were overseas fighting. The sugar beet harvest was considered crucial to the war effort, and Japanese-Americans imprisoned on the West Coast came to Colorado to work in the sugar beet fields. After the war ended, many stayed in Colorado. Prisoners of war from Germany and Italy also worked in the beet fields.

In 1950, the population of Longmont was about 8,000, and the economy was based primarily on agriculture. During the 1950s, the economy of the Colorado Front Range began to shift to high technology, and those changes soon impacted Longmont. Mayor Ralph Price, foreseeing a need for more water for a thirsty town, spearheaded the construction of Button Rock Dam in 1969, built seven miles upstream from Lyons on the North St. Vrain River. It paid for itself almost immediately, holding what could have been a disastrous flood in check and filling the reservoir in a few days rather than the years it was projected to take.

In 1962, the U.S. government built Longmont's air traffic control center. Three years later, IBM built a large facility seven miles from town. Longmont, which had grown slightly beyond its original square mile plan since 1871, doubled in size between 1960 and 1970 and between 1970 and 1980.

Events in the 1970s and 1980s forced Longmont residents to re-examine their community. Two of Longmont's long-time employers, the Kuner-Empson vegetable cannery and the Great Western Sugar factory, closed in the 1970s, leaving fewer links with Longmont's agricultural heritage. On August 14, 1980, a Longmont police officer shot and killed two Latino residents, Juan Louis Garcia and Jeff Cordova, during an altercation that followed a traffic stop. This tragedy forced the Latino and Anglo communities to work together to prevent further violence. It led to massive changes in police training and the founding of El Comite, an organization devoted to improving relations.

Recessions and cutbacks at IBM and StorageTek, a computer storage company founded by several ex-IBM employees, slowed growth during the 1980s. Rapid growth resumed in the 1990s. The 2000 census measured Longmont's population at 71,093, a jump of nearly 20,000 since 1990. Growth in high-technology businesses continued throughout the 2000s.

In September 2013, a significant flood struck Colorado's Front Range, seriously impacting Longmont. The St. Vrain River and Left Hand Creek overflowed into neighborhoods and business districts. Rebuilding and restoration began immediately. The ongoing Resilient St. Vrain Project protects Longmont from future floods and improves the river corridor in the community via ongoing improvements.

Longmont developed a municipal broadband internet service called NextLight between 2014 and 2016, consistently ranked as one of the fastest in the nation. The 2020 census recorded Longmont's population as 98,885, with the town passing 100,000 residents shortly afterward. In 2021, Longmont honored its 150th anniversary and reconnected with an essential part of its heritage by signing a historic Sister City agreement with the Northern Arapaho, the first such agreement between a city and a sovereign nation.


Erik Mason is the Curator of History at the Longmont Museum and the author of Longmont: The First 150 Years, which is available at the Museum and local bookstores.


To learn more about Longmont's History through free Virtual Tours brought to you by the Longmont Museum, visit the links below:

Downtown Longmont Walking Tour

Women of Longmont Virtual 

Latino History Virtual Tour


At Visit Longmont, we acknowledge that Longmont sits on the traditional lands of the Cheyenne, Arapaho, Ute and other Indigenous peoples, who have inhabited this region for thousands of years. We commit to educating our communities, guests, and ourselves about past injustices. We honor the history and the first peoples' living and spiritual connection with this land. We aspire to work together toward a healing path and commit to listening to elders and learning from past lessons, as these stories help weave a healthier future.


Find an Event

Show Events For
Show Events Between
Apply Changes Clear Filters


More History

Ken Pratt
Callahan House
Teddy Roosevelt
Tower of Compassion
J.C. Penney
Stephen Long