Killingly is a town in Windham County, Connecticut, United States. The population was 17,752 at the 2020 census. It consists of the borough of Danielson and the villages of Attawaugan, Ballouville, Dayville, East Killingly, Rogers, and South Killingly. History In 1653, the second John Winthrop, son of Massachusetts Bay Colony's founding governor, obtained a grant of land formerly held by the Quinebaug Indian tribe and known as the Quinebaug (Long Pond) Country. The name Quinebaug comes from the southern New England Native American term, spelled variously , , etc., meaning "long pond", from , "long", and , "pond". The area in that grant, which is now occupied by Killingly, was first settled by English colonists in 1700. It was first called "Aspinock", a word which may have come from the combination of the native term "aucks" or "ock" (the place of/where) and the name of the English settler, Lieutenant Aspinwall. When the town was incorporated in May 1708, Colony Governor Saltonstall was asked to suggest a name. Saltonstall's ancestral manorial possessions lay in Killanslie and Pontefract, Yorkshire, hence he suggested “Kellingly” (the spelling was later altered). During the 1830s, Killingly was the state's largest producer of cotton goods, manufacturing textiles in mills from cotton shipped from the Deep South. By the 1930s, it was an important producer of window curtains. Geography According to the United States Census Bureau, the town has a total area of , of which, of it is land and of it (2.94%) is water. Principal communities Attawaugan Ballouville Chestnut Hill Danielson (borough) Dayville East Killingly Elmville Killingly Center Rogers South Killingly On the National Register of Historic Places Broad Street – Davis Park Historic District – Roughly along Broad Street, from Dorrance Street to Winter Street (added 1998) Daniel's Village Archeological Site (added 1978) Danielson Main Street Historic District – Main Street from Water Street to Spring Street (added 1992), featuring Colonial Revival and Italianate architectural styles. Dayville Historic District – Main and Pleasant Streets (added 1988) Elliottville Lower Mill – Peep Toad Road (added 1982) Old Killingly High School – 185 Broad Street (added 1992) Temple Beth Israel (Danielson, Connecticut) – 39 Killingly Drive (added 2003) Demographics As of the 2010 United States Census, there were 17,370 people, 6,749 households, and 4,528 families in the town. The population density was 358.1/square mile (137.9/km). There were 7,592 housing units at an average density of 156.5/square mile