Niwot is a census-designated place (CDP) in Boulder County, Colorado, United States. The population was 4,160 at the 2000 census. The Niwot Post Office has the ZIP Code 80544. This locality is named for Arapaho Chief Niwot, a tribal leader in the Boulder area during the nineteenth century. The name means "left-handed. " With a per capita income of $39,943, Niwot is ranked as the 17th wealthiest location in Colorado.