When Kamala Harris’s mother left India for California in 1958, the percentage of Americans who were immigrants was at its lowest point in over a century.

That was about to change.

Her arrival at Berkeley as a young graduate student — and that of another student, an immigrant from Jamaica whom she would marry — was the beginning of a historic wave of immigration from outside Europe that would transform the United States in ways its leaders never imagined. Now, the American-born children of these immigrants — people like Ms. Harris — are the face of this country’s demographic future.

Joseph R. Biden Jr.’s choice of Ms. Harris as his running mate has been celebrated as a milestone because she is the first Black woman and the first of Indian descent in American history to be on a major party’s presidential ticket. But her selection also highlights a remarkable shift in this country: the rise of a new wave of children of immigrants, or second-generation Americans, as a growing political and cultural force, different from any that has come before.

The last major influx of immigrants, in the late 19th and early 20th centuries, came primarily from Eastern and Southern Europe. This time the surge comes from around the world, from India and Jamaica to China and Mexico and beyond.