It is historian Oscar Handlin's thesis that the demand that immigrants assimilate and surrender their separateness made them adjust to the American way of life; but they were treated immorally and were condemned under the shadow of consciousness that the immigrants were strangers and outsiders that would never belong.
Immigrants would come with minds and spirits fresh for new impressions; and being in America would make Americans of them. The sense of being welcome gave them the assurance that their struggles to build a new life would be regarded with sympathy. The expression of doubts that some parts of the population might not become fully American implied the existence of a settled criticism of what was truly American. There were attempts to distinguish among the natives between those who really belonged and those who didn't. All critics expressed that some hereditary element had given form to American culture, but they provided no means of social recognition and offered no basis on how the true Americans could identify themselves as such.
The experience of life in the United States had not broken down the separateness of the elements mixed into it. Long after the great immigration of Irish and Germans, these people had not become indistinguishable from other Americans; they were still recognizably Irish and German. The conclusion was inevitable: to be Americanized, the immigrants must conform to the American way of life completely defined by the way they lived.
The boldness of such judgments testified to the voluntary nature of immigration adjustment. The adjustment had depended on the immigrants' ability as individuals in a free society to adapt themselves to their environment through what forms they chose. The demand by their critics that the adjustment take a predetermined course seemed to question their right to a place...