Daniele Caramani describes the transformation of politics from an environment where voting behavior differs greatly between regions to one where it is homogeneous within nations. Looking at long-term evolution, spanning the mid-nineteenth century to the present, Caramani utilizes data on specific constituencies rather than on a national level. He demonstrates that a nation-wide homogeneous dimension emerged from national and industrial revolutions and replaced preindustrial territorial dimensions. His analysis is constructed along the lines of party families and reveals why countries currently exhibit different levels of homogeneity.