In the past two centuries, urban growth has increased at a rapid pace, mainly driven by the demographic impact of industrialization. Besides urban growth, as this article argues, effects of industrialization have likewise intensified urban shrinkage. Cities of the industrial age have experienced unprecedented economic crises followed by waves of out-migration; they have suffered from violent destruction, made possible by the mechanization of war; they have been drained by suburbanization driven by an industrialized building sector and increasing private car ownership; and they have undergone processes of deindustrialization followed by losses of workplaces and population. This article outlines the historic development of urban shrinkage in the twentieth century, with a particular focus on the aged industrial countries. Based on an extensive evaluation of historic population data, the article provides an overview of the most relevant causes of shrinking cities, and offers an outlook on future demographic trends.