The City of Longmont is a Home Rule Municipality located in Boulder and Weld counties, Colorado, United States. Longmont is located northeast of the county seat of Boulder and 33 miles (53 km) north-northwest of the Colorado State Capitol in Denver.
Longmont's population was 86,270 at the time of the 2010 U.S. Census. Longmont is the 13th most populous city in the state of Colorado.
The word "Longmont" comes from Longs Peak, a prominent mountain named for explorer Stephen H. Long that is clearly visible from Longmont, and "mont", from the French word "montagne" for mountain.
Longmont was founded in 1871 by a group of people from Chicago, Illinois. Originally called the Chicago-Colorado Colony, the men sold memberships in the town, purchasing the land necessary for the town hall with the proceeds. As the first planned community in Boulder County, the city streets were laid out in a grid plan within a square mile. The city began to flourish as an agricultural community after the building of the Colorado Central Railroad line arrived northward from Boulder in 1877. During the 1940s, Longmont began to grow beyond these original limits.
In 1925, the Ku Klux Klan gained control of Longmont 's City Council in an election.