Niwot, CO has a population of 4,588 and is the 6,852nd largest city in the United States. The population density is 1,148 per sq mi which is 2205% higher than the Colorado average and 1167% higher than the national average. The median age in Niwot is 47 which is approximately 29% higher than the Colorado average of 36. In Niwot, 64% of the population over 15 years of age are married, 92% speak English and 4% speak Spanish. 28% of Niwot residents were born in Colorado, 62% were born out of state, 1% were born outside of the United States and 9% were foreign born.