" It is important to distinguish between lead and follower countries to understand the dynamics of technological diffusion, and analyse processes of catch-up and falling behind. ‘Lead’ countries are those whose economies operate nearest to the technical frontier; ‘follower’ countries have a lower level of labour productivity (or GDP per capita). Since 1500 there have been four lead countries, northern Italy in the sixteenth century, the Netherlands from the sixteenth century until the Napoleonic wars, when the UK took over. The British lead lasted until around 1890, and the US has been the leader since then. "

― , Contours of the World Economy, 1-2030 AD: Essays in Macro-Economic History