American society, fascinating as it was, did not necessarily seem to be characterized by social cohesion, especially at the dawn of the twentieth century; neither equality nor social peace was its outstanding feature. Supported by the energy of its women and the ambition of its men, it was at the same time shaken by extensive social conflicts, by the persistence of the race problem and by the sad state of the Indian population. Yet at the same time the French observers frequently discerned characteristics common to all Americans, which made for a solid and coherent society.

In this ambiguous context, the immigrants who arrived in ever-increasing numbers on American soil constituted one of the most surprising facets of the capacities of such a society: Were the immigrants the constantly renewed proof of great assimilating power, or were they, as this population shift gained momentum, a source of weakness that could be cause for concern about its previously promising future?

The phenomenon of immigration to the United States peaked during our period. While a few hundred French visitors and a few tens of thousands of French immigrants landed in New York between 1870 and 1914, more than 20 million immigrants from all kinds of other places followed the same itinerary. The scope of the phenomenon was bound to disconcert the French, who at that point had never seen anything like it, even though by that time France had already become an immigration country for certain of its neighbors.