In his detailed study of comparative imports and exports of Britain (including the West Indies) and the newly independent American states, Sheffield provides a systematic and statistical approach to the interrelatedness of American and imperial markets. With fifteen elaborate serial tables, it remains a valuable source for accurate information on eighteenth century commerce as well as a guide to British commercial attitudes toward the empire. Sheffield was a consistent exponent of the old colonial trading system which was not effectively challenged until after the Napoleonic Wars.