Wearside (/ˈwɪərsaɪd/) is a Built-up area in both Tyne and Wear and County Durham, Northern England. It is named after the River Wear which flows through it and traditionally all in the County of Durham. In the 2011 census, its official name was the Sunderland Built-up area since Sunderland is its largest part and most of the area is within the metropolitan borough of the City of Sunderland.