Until comparatively recently, historians treated progressivism of the early twentieth century variety as if it were a purely American affair. In 1952, Eric F. Goldman argued that progressivism was ‘as exclusively national a movement as the United States ever knew’. But in the years that followed, a number of works appeared which challenged the validity of this narrowly national interpretation. Arthur Mann, in 1956, suggested that American reformers were much influenced by British social thought. Gertrude Almy Slichter drew attention to the European background of American reform in a 1960 dissertation. A number of essays then showed that progressivism itself could be regarded as part of an international movement. Peter F. Clarke pointed out that there had been a progressive movement in England which, in fact, predated the American equivalent. Kenneth O. Morgan, reviewing the nature of the links between British and American reformers, thought it meaningful to write in terms of ‘ Anglo-American Progressivism’. Other historians, looking at the matter in a more general, European context, were struck by the apparent similarities between American progressives, British Liberals or Labourites, and French and German socialists. George E. Mowry argued that American progressives should be regarded as part of western ‘social democracy’. Arthur A. Ekirch came to much the same conclusion.