Milliken, CO has a population of 6,157 and is the 5,663rd largest city in the United States. The population density is 490 per sq mi which is 884% higher than the Colorado average and 441% higher than the national average. The median age in Milliken is 32 which is approximately 12% lower than the Colorado average of 36. In Milliken, 71% of the population over 15 years of age are married, 90% speak English and 10% speak Spanish. 55% of Milliken residents were born in Colorado, 42% were born out of state, 0% were born outside of the United States and 3% were foreign born.