Aurora, CO has a population of 351,131 and is the 54th largest city in the United States. The population density is 2,287 per sq mi which is 4493% higher than the Colorado average and 2424% higher than the national average. The median age in Aurora is 34 which is approximately 6% lower than the Colorado average of 36. In Aurora, 51% of the population over 15 years of age are married, 68% speak English and 21% speak Spanish. 41% of Aurora residents were born in Colorado, 38% were born out of state, 2% were born outside of the United States and 20% were foreign born.