This paper examines the relationship between trade policy and the growth of large cities in developing countries. It argues that the rise of giant metropolises in the Third World after World War II was largely due to import-substituting industrialization policies. These policies encouraged the concentration of manufacturing in urban centers, where backward and forward linkages between firms and markets created strong economic incentives for production. However, as developing countries liberalize trade, these linkages weaken, leading to the decentralization of industry and a reduction in the size of large cities. The paper presents a theoretical model to explain how trade policy affects the geographic concentration of population and production. It shows that in a closed economy, the backward and forward linkages in urban centers create a self-reinforcing cycle of agglomeration. However, in an open economy, these linkages are weakened, and the centrifugal forces of high land rents, wages, and commuting costs become more significant. This leads to a more dispersed urban structure. The paper also highlights the importance of economies of scale and domestic market orientation in the concentration of manufacturing in urban centers. It argues that the growth of large cities is not a natural outcome but rather an unintended consequence of import-substituting industrialization policies. As these policies are replaced by more open trade policies, the growth of large cities is likely to decline. The paper concludes that trade policy has a significant impact on urban development in developing countries. It suggests that economists should pay more attention to the effects of trade policies on the internal economic geography of countries. The paper also emphasizes the need for further empirical research to confirm these theoretical arguments.This paper examines the relationship between trade policy and the growth of large cities in developing countries. It argues that the rise of giant metropolises in the Third World after World War II was largely due to import-substituting industrialization policies. These policies encouraged the concentration of manufacturing in urban centers, where backward and forward linkages between firms and markets created strong economic incentives for production. However, as developing countries liberalize trade, these linkages weaken, leading to the decentralization of industry and a reduction in the size of large cities. The paper presents a theoretical model to explain how trade policy affects the geographic concentration of population and production. It shows that in a closed economy, the backward and forward linkages in urban centers create a self-reinforcing cycle of agglomeration. However, in an open economy, these linkages are weakened, and the centrifugal forces of high land rents, wages, and commuting costs become more significant. This leads to a more dispersed urban structure. The paper also highlights the importance of economies of scale and domestic market orientation in the concentration of manufacturing in urban centers. It argues that the growth of large cities is not a natural outcome but rather an unintended consequence of import-substituting industrialization policies. As these policies are replaced by more open trade policies, the growth of large cities is likely to decline. The paper concludes that trade policy has a significant impact on urban development in developing countries. It suggests that economists should pay more attention to the effects of trade policies on the internal economic geography of countries. The paper also emphasizes the need for further empirical research to confirm these theoretical arguments.