Considering the total flow, legal and undocumented, immigration to the US has got again in these last years, to a level approaching the all-time highs recorded at the turn of the 20th century. This phenomenon has a growing importance in the US demography. But this immigration, since the end of the sixties, has known a complete change as for the origin of the migrants, with a predominant stream from the Third World. The insertion of this second « new immigration » in the US society, which reflects a growing apprehension in his public opinion, appears as the new US challenge.En comptant la totalité des flux, légaux ou illégaux, l'immigration aux Etats-Unis retrouve ces dernières années un niveau proche des records du début du XX' siècle. Son ...