Waterbury, CT has a population of 109,211 and is the 266th largest city in the United States. The population density is 3,829 per sq mi which is 491% higher than the Connecticut average and 4126% higher than the national average. The median age in Waterbury is 35 which is approximately 15% lower than the Connecticut average of 41. In Waterbury, 42% of the population over 15 years of age are married, 62% speak English and 27% speak Spanish. 57% of Waterbury residents were born in Connecticut, 16% were born out of state, 11% were born outside of the United States and 16% were foreign born.