Old Saybrook, town, Middlesex County, southern Connecticut, on Long Island Sound, at the mouth of the Connecticut River; incorporated 1854. It is primarily a residential community and a summer resort and has some manufacturing firms. The Dutch first visited the area in 1614, but no attempts were made to settle here until Saybrook, the first permanent community on the site, was established in 1635 by a group of English settlers under the leadership of the colonial governor John Winthrop. The Collegiate School of America, from which Yale University developed, was founded here in 1701, and in 1775 the American inventor David Bushnell built a submarine here that was used during the American Revolution. Saybrook (now Deep River) and Old Saybrook were separated in 1852. Population 9,287 (1980); 9,552 (1990); 10,367 (2000); 10,512 (2005 estimate).