Longmont, CO has a population of 90,719 and is the 360th largest city in the United States. The population density is 3,295 per sq mi which is 6519% higher than the Colorado average and 3537% higher than the national average. The median age in Longmont is 37 which is approximately 1% higher than the Colorado average of 36. In Longmont, 56% of the population over 15 years of age are married, 79% speak English and 17% speak Spanish. 40% of Longmont residents were born in Colorado, 47% were born out of state, 1% were born outside of the United States and 12% were foreign born.