Sterling, CO has a population of 13,976 and is the 2,991st largest city in the United States. The population density is 1,835 per sq mi which is 3586% higher than the Colorado average and 1926% higher than the national average. The median age in Sterling is 34 which is approximately 6% lower than the Colorado average of 36. In Sterling, 45% of the population over 15 years of age are married, 92% speak English and 7% speak Spanish. 56% of Sterling residents were born in Colorado, 38% were born out of state, 2% were born outside of the United States and 4% were foreign born.