Old Greenwich, CT has a population of 7,000 and is the 5,177th largest city in the United States. The population density is 3,508 per sq mi which is 442% higher than the Connecticut average and 3772% higher than the national average. The median age in Old Greenwich is 40 which is approximately 3% lower than the Connecticut average of 41. In Old Greenwich, 73% of the population over 15 years of age are married, 72% speak English and 10% speak Spanish. 28% of Old Greenwich residents were born in Connecticut, 46% were born out of state, 3% were born outside of the United States and 24% were foreign born.