Boulder County is the sixth most populous of the 64 counties of the State of Colorado of the United States. The United States Census Bureau estimates that the county population was 322,226 in 2016. The county seat is the City of Boulder.
History
Boulder County was one of the original 17 counties created by the Territory of Colorado on 1861-11-01. The county was named for Boulder City and Boulder Creek, so named because of the abundance of boulders in the area.
