Primarily Indians inhabited the area surrounding Longmont before the arrival of the Chicago-Colorado Colony in 1871. Arapahoes and Utes were the most recent Native American tribes in the area, but gradually they were replaced by Spanish gold seekers, newcomers and the military brought in for their protection.

In 1820, Major Stephen H. Long passed through while exploring the South Platte River. Longs Peak to the west is named for him, as is the city of Longmont.

The discovery of gold in California in 1849 saw many treasure seekers passing through Colorado on their way west. The same gold fever enticed many to the Pikes Peak, Central City and Boulder regions in 1858­59. Many knew how to farm and settled in the fertile St. Vrain Valley.

Alonzo M. Allen and his stepson William H. Dickens settled on the St. Vrain River south of present Longmont in 1859. Here they built the first log cabin in the vicinity. Gradually others settled followed suite and the town of Old Burlington came to life. By 1862, it was large enough to boast a U.S. Post Office and a "swing stop" station on the stage line between Denver and other points to the north.

About this time a group of Chicago citizens became interested in establishing a colony in the Colorado territory. In January of 1871, after the formation of the colony in Chicago, Chicago-Colorado Colony officials sent Seth Terry to locate the site. He went as far north as Loveland and Fort Collins and finally settled on the Old Burlington area. Terry was impressed with the possibilities of the available rich farmland and the amount of water in the St. Vrain River.

The town of Longmont was laid in a square mile bounded by present First Avenue on the south, Martin Street on the east, Ninth Avenue on the north and Bowen Street on the west. Wide streets and alleys were surveyed, residence and business lots sold to colony members, and the task of building the new town was under way. Most of the first colonists were well to do easterners. Three words motivated many people to join the colony: industry, temperance and morality. These ideals were to form a basis for colony membership for many years.