April 1974 gebildet und entstand aus der Fusion des Urban Districts Spennymoore und Shildon, des Rural District Sedgefield sowie eines Teils des Rural District Darlington. ###>The borough was formed in 1974, under the Local Government Act 1972, by the merger of Sedgefield Rural District, Spennymoor and Shildon urban districts and part of Darlington Rural District.