South Lancashire is a geographical county area, used to indicate the southern part of the historic county of Lancashire, today without any administrative purpose. The county region has no exact boundaries but generally includes areas that form the West Derby Hundred and the Salford Hundred, both of which formed the South Lancashire parliament constituency from 1832. This constituency was further divided in 1868 forming the South East Lancashire and South West Lancashire constituencies. Today the area is still recognized by the government and organisations, including the National Health Service. South Lancashire includes the cities of Manchester and Liverpool.
In 1881, the South Lancashire Regiment was formed with the barracks located in Warrington. The regiment primarily recruited around the South Lancashire area.
Following reforms of local government and the Local Government Act 1972, the majority of South Lancashire fell into the administrative counties of Greater Manchester and Merseyside, however South Lancashire is still recognized and in use today.
The rivalry fixtures between Bolton Wanderers and Wigan Athletic is sometimes referred to as the South Lancashire derby.