The article discusses political development in the paradigmatic cases of Western Europe and the United States, arguing that the building and consolidation of their democratic nation states follow different paths. Nevertheless, after two centuries of differential political and institutional evolution, at the end of the 20th century, Western Europe, with the deepening of the integration process, has moved in the direction of a supranational organization that has many similarities to the American compound republic. However, the different institutional histories, with their attendant path-dependency effects, will continue to condition the developments of Europe and America, rendering convergence toward uniformity highly unlikely. Notwithstanding institutional transformation occurring in the Western political world, plurality will continue to mark its future.