So what explains the persistent drumbeat about the impending white minority? A statistical distortion: the exclusion of Hispanic whites. If only non-Hispanic whites are counted, the white population today amounts to 66 percent of the total, and will hit around 46 percent by 2050.

But excluding whites of Hispanic origin from the overall white population makes no more sense than excluding whites of Slavic or Scandinavian origin. “Hispanic” is not a race. It is an ethnic category. As the Census Bureau repeatedly points out, Hispanics can be of any race. In the 2000 census, 48 percent of Hispanics identified themselves as white; Harvard sociologist Orlando Patterson has characterized them as “white in every social sense of this term.” Bottom line: Of the 46.6 million Hispanics in the United States today, at least 22 million are white.

On both right and left, however, there are pressures to treat Hispanics as a distinct racial category. Many on the left covet the political attention and affirmative-action largesse that comes with minority-group status. In some quarters of the right, meanwhile, immigration alarmists warn that Hispanics are overwhelming the nation’s “white” culture, dissolving the bonds of language and patriotism on which American civilization depends.

One of the lessons of US history is that racial categories are anything but meaningful scientific classifications. For generations, “whites” have been hearing that they are about to be engulfed by unassimilable foreign races, and for centuries those “races” have eventually become - white! Benjamin Franklin worried mightily about the threat posed to white American culture by the influx of German immigrants. “Why should Pennsylvania, founded by the English, become a Colony of Aliens,” he demanded in 1751, “who will shortly be so numerous as to Germanize us instead of our Anglifying them?” Those “swarthy” Germans, Franklin was quite sure, “will never adopt our Language or Customs, any more than they can adopt our Complexion.”

A century and a half later, Senator Henry Cabot Lodge witheringly described the Russians, Poles, and Greeks entering the country as “races with which the English-speaking people have never hitherto assimilated, and who are most alien to the great body of the people of the United States.” In the early 20th century, federal immigration officials classified the Irish, Italians, and Jews as separate races. Yet today all these groups are viewed collectively, and benignly, as “white.”

And so, in time, will Hispanics, who give every indication of being just as assimilable as earlier groups. Most third-generation Hispanic Americans, for example, marry non-Hispanics. The overwhelming majority speak English. With a little luck, common sense, and goodwill, it will seem as odd in 2050 to focus on “non-Hispanic whites” as it would today to insist that only “non-German whites” are really white.

Better still, perhaps by then we will have really progressed, and abandoned the pernicious notion of racial categories altogether.

Jeff Jacoby’s e-mail address is jacoby@globe.com.

Source: Boston