The first permanent settlement in Adams County was established by Colonel Jack Henderson on a large island in the South Platte River about seven miles southwest of Brighton. The Henderson area soon became home to a number of settlers, most of whom had come west to strike it rich during the "gold rush". These first residents of the county soon discovered there was more money in raising crops and livestock to supply prospectors and the new city of Denver, than there was in gold mining. Previously, food had to be shipped in from New Mexico or points east. The early farmers of Adams County helped make the growth of Denver possible and established the agricultural economy that much of the county still depends on today.

The first railroad depot in Adams County was named Hughes after the first president of the railroad. The name was later changed to Brighton when Daniel F. Carmichael, a Denver real estate agent, filed the first plat for a town, but rather than Hughes, it was named Brighton. In 1887, Brighton became the first incorporated town in the territory.

Forming of the County

In 1902, voters approved creation of Adams County which, prior to that time, had been part of an enormous Arapahoe County. The county was named after Alva Adams, a popular former governor who was in office at the time of this election. The county courthouse was temporarily housed in the residence of Daniel Carmichael (the founder of Brighton) in Brighton. After a fire destroyed these offices in January 1904, the offices were relocated to a rented house at 3rd and Bridge Street in Brighton.

In an election held November 8, 1904, Brighton was chosen as the permanent county seat and, as was befitting a new and prosperous county, a new courthouse was built at 4th and Bridge Street in 1906. That building still stands as the eastern half of the Brighton City Hall.