Arlington Heights, IL has a population of 75,721 and is the 464th largest city in the United States. The population density is 4,561 per sq mi which is 1952% higher than the Illinois average and 4935% higher than the national average. The median age in Arlington Heights is 44 which is approximately 17% higher than the Illinois average of 37. In Arlington Heights, 66% of the population over 15 years of age are married, 77% speak English and 3% speak Spanish. 65% of Arlington Heights residents were born in Illinois, 16% were born out of state, 1% were born outside of the United States and 18% were foreign born.