How Adams County got its name and its start

Adams County is younger than the towns inside it, and the short version of how it began helps the map make sense.

In the early 1900s, the Colorado legislature split the large old Arapahoe County, and the northern piece became Adams County, with Brighton as its seat. The new county was named for Alva Adams, who served as a Colorado governor. So unlike many Colorado place names that come from a mine, a river, or a railroad stop, this one honors a person in state politics.

There is a local thread too. A Brighton-area rancher and large livestock owner, Emmet Bromley, was behind the push to create the county. His name still turns up on the land: the Bromley Farm in Brighton, later farmed by a Japanese American family, is a preserved historic site today.

Why this matters beyond trivia: knowing the county was carved out of Arapahoe County in the early 1900s, recent by the terms of state history, explains why its boundaries, its courthouse in Brighton, and its mix of farm and suburb feel layered. It grew up fast around older farm communities.

For the documented founding story and the people behind it, start with the Colorado Encyclopedia and History Colorado.