Glasgow, like Liverpool, was of little consequence when Britain's interest lay in Europe. Though its regional status attracted craftsmen and traders, its mercantile sector lacked connections, capital, ships and expertise. Most Glasgow trade passed through the Forth. Change came, slowly, with the creation of "English" settlement and plantation colonies. Glasgow's merchants were adept at supplying the manufactures and goods of everyday life to the West of Scotland and Ireland and these were in great demand in early non-self-sufficient colonies. Unable to compete with London tobacco Agents selling on commission, Glasgow merchants shipped coal, cloth and manufactures from c.1672 and established "stores", extending credit or directly purchasing tobacco and sugar. Either way, colonial producers were indebted to Glasgow.
Transatlantic trade increased rapidly after 1707, partly because of the Union, but chiefly because of integrated trade and industrial developments. The production of linen increased and cotton wool from the West Indies created a new industry by the 1740s. Imported sugar fed the Glasgow Sugar House and distilleries; the glassworks served an imperial market; which in turn provided barrel staves. By the 1740s Glasgow was the major port in the tobacco trade with a dedicated fleet. For a country lacking foreign exchange, tobacco paid for vital European raw materials and sustained the cycle of export, import and re-export that made Glasgow a leading industrial port in the British Empire. Important though the European raw materials might be, it was the transatlantic trade which created the wealth and encouraged the shipping of Glasgow and its transhipment ports of Port Glasgow and Greenock.