National accounts and census data imply that agricultural productivity gaps have been remarkably persistent over the last few decades, in spite of declining shares of employment in agriculture. This paper builds a quantitative theory of these trends featuring imperfect mobility of labor across sectors, frictional international trade, and uneven movements of sectoral relative prices and real productivity levels. Agricultural productivity gaps persist in the model if relative prices or productivities of non-agricultural goods rise faster than labor can move out of agriculture to close the gaps. We estimate the model to match time series patterns of exports by sector and country, as well as sectoral employment shares. Quantitatively, the model explains the bulk of the cross-country variation in gap persistence, including the rising gaps in China and India.
