[1][2][3] The canal eventually connected St Helens to the River Mersey at Spike Island in Widnes.

The Sankey Canal was built principally to transport coal from Haydock Collieries and Parr to the growing chemical industries of Liverpool, although iron ore and corn were important cargoes.

[1] The industries rapidly expanded, and spread along the line of the canal to St Helens, Haydock, Newton le Willows and Widnes, which were small villages until this period.

"[5] The canal was open and carrying coal by 1757;[6] carriage of all goods was charged at a flat rate of 10d (ten old pence – £0.04, equivalent to £7 when adjusted for inflation) per ton.

[8] An early trial of steam power took place[7] on 16 June 1797, when, according to the Billing's Liverpool Advertiser, dated 26 June, John Smith's "vessel heavily laden with copper slag, passed along the Sankey Canal ... by the application of steam only ... it appears, that the vessel after a course of 10 miles [16 km], returned the same evening to St Helens whence it had set out".

4. c. l), granted on 29 May 1830, entitled "An Act to consolidate and amend the Acts relating to the Sankey Brook Navigation, in the county of Lancaster; and to make a New Canal from the said Navigation at Fidler's Ferry, to communicate with the River Mersey at Widness Wharf, near West Bank, in the township of Widnes, in the said county".

The exception was near the newly built town in Newton-Le-Willows that was to become Earlestown, where George Stephenson erected the Sankey Viaduct for the Liverpool and Manchester Railway, leaving 70-foot (21 m) headroom for the flats' sails.

Built primarily to take coal from Haydock and Parr down to the Mersey and so on to the saltfields of Cheshire and Liverpool, the final traffic on the Sankey Canal was very different, and in the opposite direction, consisting of raw sugar for the Sankey Sugar Works at Earlestown, Newton-le-Willows, from Liverpool.

In 1877, it was reportedly the case that, due to the pollution of a local Leblanc alkali works, "The mud deposited in the Sankey Brook, near St Helens, has been found to contain no less than 2.26 percent of arsenic ...

[12] Reportedly, by 1891, 500 acres (2.0 km2) of nearby Widnes and Ditton Marshes were buried under an average depth of 12 feet (3.7 m) of toxic galligu from alkali operations near the Sankey Canal.

There are, however, plans to dig out an infilled section in the centre of St Helens as part of the town's Eastside development.

It actually comprises nine sandstone arches, with a 60-foot (18.3m) minimum clearance above the canal, which was required to allow the masts of the Mersey flats to clear.