Collinsville, CT has a population of 3,693 and is the 7,799th largest city in the United States. The population density is 1,178 per sq mi which is 82% higher than the Connecticut average and 1201% higher than the national average. The median age in Collinsville is 47 which is approximately 16% higher than the Connecticut average of 41. In Collinsville, 67% of the population over 15 years of age are married, 88% speak English and 7% speak Spanish. 60% of Collinsville residents were born in Connecticut, 31% were born out of state, 1% were born outside of the United States and 8% were foreign born.