Deep River is a town in Middlesex County, Connecticut. The population was 4,415 at the 2020 census. The town center is designated by the U.S. Census Bureau as a census-designated place (CDP). Deep River is part of what the locals call the "Tri-town Area", made up of the towns of Deep River, Chester, and Essex. Geography According to the United States Census Bureau, the town has a total area of , of which is land and (4.30%) is water. The CDP has a total area of , of which 4.38% is water. Principal communities Deep River Center Winthrop History Saybrook Colony formally joined Connecticut in 1644. The portion of the original colony east of the Connecticut River was set off as a separate town in 1665. The site of the present village of Deep River was said to have been owned by John, Nathaniel, and Philip Kirtland in 1723. The village of Winthrop was said to have been settled by Baptists as early as 1729. In the early to mid-19th century, various portions of Saybrook broke off as separate towns, starting from Chester in 1836 to Old Saybrook in 1854. In 1947, the town of Saybrook changed its name to "Deep River", matching the name of the town center village. The name "Deep River" was taken from the river/stream that once powered mills and factories that runs through it and not from the Connecticut River that is its eastern border. The actual Deep River stream begins at the border of its neighboring Town of Chester, in the western Winthrop section of town, on Cedar Swamp Road and flows through town to the stream that can be seen on Route 154, near Winter Avenue, empty onto the cove that connects to The Connecticut River. Source: Deep River,the Illustrated Story of a Connecticut River Town by Daniel J. Connors, 1966, The Pequot Press, Stonington, Ct. pages17, 19, 20, 27, 37,41, also "Wharf to Waterfall" permanent exhibit, Deep River Historical Society, Inc. 245 Main Street, Deep River, CT 06417, 2020–21 Towns created from Saybrook Colony Saybrook Colony, along the mouth of the Connecticut River, was one of the early settlements in the area. Several towns broke off and incorporated separately over the course of time. The towns which were created from parts of Saybrook Colony are listed below. Lyme (originally East Saybrook) in 1665 East Lyme created from Lyme in 1839 (also partly