Willimantic, CT has a population of 17,339 and is the 2,488th largest city in the United States. The population density is 3,943 per sq mi which is 509% higher than the Connecticut average and 4252% higher than the national average. The median age in Willimantic is 27 which is approximately 34% lower than the Connecticut average of 41. In Willimantic, 27% of the population over 15 years of age are married, 59% speak English and 35% speak Spanish. 55% of Willimantic residents were born in Connecticut, 16% were born out of state, 14% were born outside of the United States and 14% were foreign born.