This was a period of great turmoil in international trade and Glasgow shared the uncertainties. World War One, the inter-war Depression and World War Two decimated European trade and though Glasgow was not so committed to that region as many ports, its trade suffered. However, the long-standing transatlantic and general imperial connections were strengthened and very large quantities of wide-ranging foodstuffs continued to arrive, encouraged from 1922 by "Sterling Area" legislation to preserve the balance of payments. In reverse, emigration schemes designed to relieve UK unemployment and foster imperial production and infrastructure, stimulated increased flows of goods and people to the Dominions, Africa and, to some extent, the Far East. Malaya produced tin and Glasgow built the tin dredges. The success of Hong Kong and Shanghai as entrepôts for British exports further encouraged the shipping that cruised the Yangtse and sailed the China Coast (except in wartime) until the Communist take-over in 1949.
The strength of Glasgow's trade in this period lay in its west coast location and experience in global long-haul trades. No other Scottish port – only Liverpool in Britain – exceeded its mercantile connections and shipowning enterprise. Exports were now drawn from the whole of industrial Scotland. The vast schedule expanded slightly, but it still consisted principally of 19th century products: coal, metal goods, railway goods and ships, heavy linen and jute products, ropes, textiles, thread, carpets, paints, chemicals (including dyestuffs), and the inevitable tobacco, "Export" beer to the east and whisky to the west, the latter hampered by the years of "Prohibition". Without exaggeration this was Glasgow's pinnacle as the "Workshop of the Empire".