Horwich is a town and civil parish in the Metropolitan Borough of Bolton. Historically in Lancashire, it is 5.3 miles (8.5 km) southeast of Chorley, 5.8 miles (9.3 km) northwest of Bolton and 15 miles (24 km) northwest of Manchester. It lies at the southern edge of the West Pennine Moors with the M61 motorway passing close to the south and west. At the 2011 Census, Horwich had a population of 20,067.

Horwich emerged in the Middle Ages as a hunting chase. Streams flowing from the moors were harnessed to provide power for bleachworks and other industry at the start of the Industrial Revolution. The textile industry became a major employer and after 1884 the construction of the railway works caused the population of the town to increase dramatically. The old industries have closed and urban regeneration has been led by out of town developments, particularly at Middlebrook, which, since 1997 has been the base of Bolton Wanderers football club, who play at the University of Bolton Stadium, having moved from Burnden Park near Bolton town centre.

In spring 1884 the Lancashire and Yorkshire Railway (L&YR) began construction of a large complex for building and maintaining locomotives to replace its works at Miles Platting. Horwich Works was built on 142 hectares of land bought for £36,000. The first workshop, Rivington House opened in February 1887. It is 106.7 metres long by 16.8 metres wide. The long brick built workshops had full-height arched windows and were separated by tram and rail tracks. Work to construct the three-bay, 463.3 metres long, 36 metres wide, erecting shop began in March 1885. Inside it were 20 overhead cranes. By November 1886 the first locomotives arrived at the works for repair. The first Horwich built locomotive, Number 1008, left the works in 1887 and is preserved at the National Railway Museum.

In the First and Second World War, the works played a part in the war effort manufacturing tanks and munitions.

The L&YR amalgamated with the London and North Western Railway in 1922 becoming a constituent of the London, Midland and Scottish Railway, (LMS) in 1923. Horwich Works continued to build and repair locomotives for the LMS until the company was nationalised in 1948 by the Transport Act 1947, becoming British Railways. In 1962, British Railways transferred control of its main works to British Railways Workshops Division, with its headquarters in Derby. In 1970 it was renamed British Rail Engineering Limited (BREL).

The last steam locomotive built at Horwich Works left on 27 November 1957 and the last diesel built there left on 28 December 1962. It was reduced to repairing engines and maintaining railway wagons. On 18 February 1983 BREL announced that the works would close at the end of the year. Protest marches and spirited trade union resistance failed to alter the decision and at 1 pm on Friday, 23 December 1983 Horwich Works closed after 97 years. The freehold of the railway works site was transferred from British Rail to Bolton Council in the mid-1990s.

A proposal to demolish the works and build 1,700 homes and a school was submitted to Bolton Council in early 2010. The initial phase of the development commenced in 2019.

Asbestos used to insulate steam engines and railway carriages linked to mesothelioma has been a legacy affecting former workers and their families with asbestos dust also being carried in clothing. The redevelopment of the site required it to be cleared of contaminants before building commenced. Part of the site is planned for demolition for the creation of a link road in 2019, linking the Middlebrook Retail Park, M61 and Horwich Railway Station.