It lies within the traditional and ceremonial area of County Durham but on 1 April 1997 become a unitary authority with the name Darlington Borough Council, and so is not governed by Durham, but it does share police and fire services with its former county. It borders County Durham, North Yorkshire, and Stockton-on-Tees.The current borough was formed on 1 April 1974 by the merger of the Borough of Darlington with Darlington Rural District. Places within the borough boundaries apart from Darlington include Hurworth-on-Tees.

The town’s grand North Road Station, which was built in 1842, was one of the Stockton & Darlington Railway’s show piece buildings and now houses the Darlington Railway Centre & Museum where you can see Locomotive No. 1 and a host of other memorabilia that recalls Darlington’s railway heritage. A rather more controversial memorial to the industry can be found at Morton Park where there is a 130ft long replica of the Mallard steam locomotive built entirely from red bricks.

On 14th July 2005 following the 7 July 2005 London bombings, areas of Darlington town center were closed while controlled explosions were carried out. The first incident was reported around 1745 BST, when a rucksack was seen in a phone box in Northgate, which led to evacuations of nearby shops and offices. Three controlled explosions were carried by a unit from Catterick Garrison, but Durham police said the bag only contained clothing and personal items. At around the same time staff from a nearby fire station spotted two men acting suspiciously around bins in a car park.
Firemen went to investigate and heard beeping sounds coming from one of the containers. Police immediately sealed off nearby roads causing Darlington town centre to be brought to a standstill.