Area . Opened in 1792 and named for an English seaport. Community centres: Oshawa, Whitby, Brooklin, Ashburn and Myrtle. The Town of Oshawa was also located in the county. In 1855 the Town of Whitby was incorporated in part of Whitby Township. Scugog Township was formed from a portion of Reach Township and Cartwright Township in adjoining Northumberland and Durham County in 1856. And in 1858, the Township of East Whitby was formed from the eastern portion of Whitby Township. A number of villages were also incorporated as separate municipalities in the county after it was created: Port Perry in 1871, Uxbridge in 1872, Cannington in 1878 and Beaverton in 1884. In the 20th century, the wartime town of Ajax, located in Pickering Township, was incorporated as an improvement district in 1950. It became a town in 1955. The Village of Pickering was incorporated as a village in 1953. On January 1, 1974, the portion of Ontario County south of the Trent–Severn Waterway and about half of adjacent Durham County were amalgamated as the Regional Municipality of Durham. The remaining portions of Durham County were transferred to other neighbouring counties, and the portion of Ontario County north of the Trent–Severn Waterway (Rama and Mara Townships) was transferred to Simcoe County. In addition, the part of Pickering Township west of the Rouge River (West Rouge and Port Union) was transferred to the Borough of Scarborough in the Municipality of Metropolitan Toronto. At this time Ontario and Durham counties were dissolved. Whitby served as the "County Town" or county seat and as such was the location for the county offices, courthouse and land registry office. It continues in this role for Durham Region today. See also List of census divisions of Ontario List of townships in Ontario References Province of Ontario -- A History 1615 to 1927 by Jesse Edgar Middleton & Fred Landon, copyright 1927, Dominion Publishing Company, Toronto External links History Book: "County of Ontario" by John Edwin Chandler Farewell http://www.archives.gov.on.ca/english/on-line-exhibits/maps/counties/ontario.aspx (snapshot from archive.org) Former counties in Ontario 1800 disestablishments in Canada 1852 establishments in Ontario 1974 disestablishments in Ontario Populated places disestablished in 1974 States and territories established in 1792 History of the Regional Municipality of Durham