The canal is connected to the Manchester Ship Canal via a lock at Cornbrook; to the Rochdale Canal in Manchester; to the Trent and Mersey Canal at Preston Brook, southeast of Runcorn; and to the Leeds and Liverpool Canal at Leigh. It once connected with the River Mersey at Runcorn but has since been cut off by a slip road to the Silver Jubilee Bridge.
Often considered to be the first true canal in England, it required the construction of an aqueduct to cross the River Irwell, one of the first of its kind. Its success helped inspire a period of intense canal building in Britain, known as Canal Mania. It later faced intense competition from the Liverpool and Manchester Railway and the Macclesfield Canal. Navigable throughout its history, it is one of the few canals in Britain not to have been nationalised, and remains privately owned. Pleasure craft now use the canal which forms part of the Cheshire Ring network of canals.
Francis Egerton, 3rd Duke of Bridgewater, owned some of the coal mines dug to supply North West England with fuel for the steam engines instrumental in powering England's Industrial Revolution. The duke transported his coal along the Mersey and Irwell Navigation and also by packhorse, but each method was inefficient and expensive; river transport was subject to the vagaries of river navigation, and the amount of coal packhorses could carry was limited by its relative weight. The duke's underground mines also suffered from persistent flooding, caused by the geology of the Middle Coal Measures, where the coal seam lies beneath a layer of permeable sandstone.
Having visited the Canal du Midi in France and watched the construction of the Sankey Canal in England, the duke's solution to these problems was to build an underground canal at Worsley, connected to a surface canal between Worsley and Salford. In addition to easing overland transport difficulties and providing drainage for his mines, an underground canal would provide a reliable source of water for the surface canal, and also eliminate the need to lift the coal to the surface (an expensive and difficult proposition). The canal boats would carry 30 long tons (30 t) at a time, pulled by only one horse – more than ten times the amount of cargo per horse that was possible with a cart. The duke and his estate manager John Gilbert produced a plan of the canal, and in 1759 obtained an Act of Parliament, enabling its construction.
James Brindley was brought in for his technical expertise (having previously installed a pumping system at the nearby Wet Earth Colliery), and after a six-day visit suggested varying the route of the proposed canal away from Salford, instead taking it across the River Irwell to Stretford and thereon into Manchester. This route would make connecting to any future canals much easier, and would also increase competition with the Mersey and Irwell Navigation company. Brindley moved into Worsley Old Hall and spent 46 days surveying the proposed route, which to cross the Irwell would require the construction of an aqueduct at Barton-upon-Irwell. At the duke's behest, in January 1760 Brindley also travelled to London to give evidence before a parliamentary committee. The duke therefore gained a second Act of Parliament, which superseded the original.