Putnam, CT has a population of 7,129 and is the 5,120th largest city in the United States. The population density is 2,211 per sq mi which is 241% higher than the Connecticut average and 2340% higher than the national average. The median age in Putnam is 39 which is approximately 5% lower than the Connecticut average of 41. In Putnam, 45% of the population over 15 years of age are married, 94% speak English and 2% speak Spanish. 63% of Putnam residents were born in Connecticut, 34% were born out of state, 1% were born outside of the United States and 3% were foreign born.