It was named after Sedgefield, but its largest town was Newton Aycliffe.
Other places included Shildon, Ferryhill and Spennymoor.
The borough was abolished as part of the 2009 structural changes to local government in England.
From 1983 to 2007, most of the district was represented in parliament by Tony Blair, who became Leader of the Labour Party in 1994, and Prime Minister in 1997.
This County Durham location article is a stub.