Westminster, CO has a population of 111,770 and is the 256th largest city in the United States. The population density is 3,522 per sq mi which is 6975% higher than the Colorado average and 3788% higher than the national average. The median age in Westminster is 36 which is approximately equal to the Colorado average of 36. In Westminster, 57% of the population over 15 years of age are married, 83% speak English and 10% speak Spanish. 49% of Westminster residents were born in Colorado, 40% were born out of state, 1% were born outside of the United States and 10% were foreign born.