Darlington is a unitary authority area in the ceremonial county of County Durham, north-east England. It borders the non-metropolitan county of County Durham to the north and west, to the east and North Yorkshire to the south along the line of the River Tees. The urban centre of the borough is the town of Darlington and is a major component of the Tees Valley economic area. In 2011 it had a resident population of 106,000.

Traditionally part of County Durham, the current borough boundaries were formed on 1 April 1974 by the creation of a new non-metropolitan district of Darlington by the Local Government Act 1972, covering the previous county borough of Darlington along with nearly all of Darlington Rural District (the Newton Aycliffe parts of which went to Sedgefield). It remained part of County Durham until gaining "independence" as a unitary authority on 1 April 1997. For ceremonial purposes it remains part of County Durham with whom it continues to share certain local services such as Fire and Rescue and Police. It is included within the Tees Valley area for both cultural and regional government administration.

It is made up of 24 council wards, twenty within the town of Darlington itself, which are also covered by the Darlington parliamentary constituency and four rural wards of Heighington & Coniscliffe, Hurworth, Middleton St George and Sadberge & Whessoe (part of the Sedgefield parliamentary constituency.

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