Colchester, CT has a population of 4,475 and is the 6,947th largest city in the United States. The population density is 1,001 per sq mi which is 55% higher than the Connecticut average and 1005% higher than the national average. The median age in Colchester is 41 which is approximately equal to the Connecticut average of 41. In Colchester, 51% of the population over 15 years of age are married, 96% speak English and 0% speak Spanish. 67% of Colchester residents were born in Connecticut, 29% were born out of state, 1% were born outside of the United States and 3% were foreign born.