Birkenhead /ˌbɜːrkənˈhɛd/ is a town within the Metropolitan Borough of Wirral in Merseyside, England. Historically in Cheshire, it is on the Wirral Peninsula, along the west bank of the River Mersey, opposite the city of Liverpool. The Birkenhead Urban Area defined as the contiguous built-up area along the eastern side of the Wirral had a total population of 325,264 in the 2011 Census. In the 2011 census, the Parliamentary constituency of Birkenhead had a population of 88,818. The Birkenhead and Tranmere electoral ward, covering a much smaller area, had a population of 15,879.