In the mid-18th century the growing towns of Yorkshire, including Leeds, Wakefield and Bradford, were trading increasingly. While the Aire and Calder Navigation improved links to the east for Leeds, links to the west were limited. Bradford merchants wanted to increase the supply of limestone to make lime for mortar and agriculture using coal from Bradford's collieries and to transport textiles to the Port of Liverpool. On the west coast, traders in the busy port of Liverpool wanted a cheap supply of coal for their shipping and manufacturing businesses and to tap the output from the industrial regions of Lancashire. Inspired by the effectiveness of the wholly artificial navigation, the Bridgewater Canal opened in 1759–60. A canal across the Pennines linking Liverpool and Hull (by means of the Aire and Calder Navigation) would have obvious trade benefits.