Killingly is a town located in the U.S. state of Connecticut. It is within Windham County that includes the borough of Danielson and the villages of Attawaugan, Ballouville, Dayville, East Killingly, Rogers, and South Killingly. It has a total area of 50.0 square miles at 41°49′53″N 71°51′01″W. The elevation is 449 feet above sea level. As of the 2010 census data, it had a total population of 17,370. Recent job growth is positively increased by 1.47 percent. The average travel time is 22 minutes. It has Zip codes 06239, 06241, and 06243.