During the late 18th century Glasgow became the wholesale capital of western Europe. Its merchants dealt in huge consignments of tobacco and sugar imported from North America and the Caribbean and exported goods needed by plantation owners. As in most wholesale businesses very little of these commodities ever found their way to the city, but were re-exported mostly to continental countries. With the growth of the textile trades in the early 19th century, great agency houses, such as James Finlay & Sons, were established. These dealt in consignments of cloth both for the home and export market and also imported goods for domestic consumption such as tea and sugar. The city's wholesalers and warehousemen also began to supply tools and fancy goods sold by pedlars at fairs throughout rural Scotland. Some of these firms evolved into specialist factors of machine tools and engineering products, such as P & W MacLellan, and others became wholesalers to the retail trade, sometimes owning their own shops, such as Arthur & Co.
At the same time as Glasgow became more and more reliant on imported produce, the wholesale trades in food and provisions became increasingly specialised. Those firms that dealt in goods that did not perish, such as whisky, themselves began to export both to England and to foreign markets where Scots had settled. Like their predecessors these wholesale merchants were often simply brokers, arranging the purchase and shipment of goods but never actually handling them. By the 1830s there were more merchants and brokers trading in Glasgow than any other type of business.