Abstract
Urban primacy emerged in many developing countries during the twentieth century. The author of this cross-national study applies generalized least-squares panel regressions of world-system position, level of economic development, and land area to a standardized urban primacy index. Although core nations remained stable, peripheral and semiperipheral nations became more primate from 1930 to 1970. The trend toward higher urban primacy among peripheral nations slackened dramatically in the 1970s. National city-size distributions clearly diverged in the twentieth century, and world-systems theory provides insight into the international influences that mediate internal urban processes.