WASHINGTON – White Americans, and black Americans too, are going to have to get used to sharing this country – sharing it fully – with brown Americans. Things are going to be different. Deal with it.

The most important legacy of the histrionic debate over immigration reform will not be any piece of legislation, whether enlightened or medieval. It will be the big demonstrations held in cities throughout the country over the past few weeks – mass protests staged by and for a minority whose political ambition is finally catching up with its burgeoning size. In the metaphorical sense, Latinos have arrived.

In the physical sense, of course, Latinos have been arriving for many years, and in huge numbers. In some cities they have sought and achieved political power – if there were such a thing as “the capital of Latin America,” arguably it would be Miami. As a presence in national politics, however, Latinos have been much less influential than their weight in the population would suggest.

That just began to change.

Half a million people marched in Los Angeles, another half-million in Dallas, hundreds of thousands elsewhere, including Monday here. The fact that so many undocumented immigrants came out of the shadows, giving up their safe anonymity to denounce legislation threatening their interests, wasn’t the most remarkable thing. More significant was that so many fully enfranchised Latino citizens joined them in support.

What happens next won’t look like the civil rights struggle that African-Americans waged – the nation’s two biggest minorities have different histories and face different issues, and anyway it’s a different era. I doubt that any single Latino leader will emerge, or even any single leadership group. And the advance won’t be linear or continuous, because much of the Latino population lacks full citizenship and thus can’t vote.

When I was in Phoenix last week, I talked to advocates of a round-‘em-up, kick-‘em-out policy on illegal immigration who predicted the protests would spark an Anglo backlash. Maybe it will, but everyone should remember that demography is destiny: Given the youthfulness of the Latino population, xenophobes could construct an Adobe Curtain along the length of the Mexican border next week (they’d probably use Mexican labor) and the political strength of Latinos in the United States would still continue to grow.

There are economists, I realize, who argue that illegal immigration – mostly from Mexico – has depressed wages for unskilled labor, to the detriment of low-income, native-born African-Americans and whites. Other economists disagree, and in any case the effect is generally estimated to be somewhere between negligible and small. There’s no reason employers can’t be required to pay a living wage to every janitor, whether his name is John or Juan.

But I don’t think the immigration debate is really about economics anyway. It’s about culture and it’s about fear.

Among other things, it’s about this voice-mail message: Para continuar en espanol, oprima el numero dos. To continue in Spanish, press 2.

Many Anglos in Phoenix and elsewhere were surprised by the size of the protests two weeks ago, but the demonstrations were coordinated and publicized in the open, on Spanish-language radio. Latino immigrants in this recent wave, whether they intend to stay permanently or just work for a while and go home, are learning English but also keeping their Spanish – and the fact is the United States now has a de facto second language. That seems to frighten a lot of people.

Some academics, such as the Harvard political scientist Samuel P. Huntington, have warned that unchecked Latino immigration is bringing with it alien cultural values – that somehow the Anglo-Saxon-ness of the country is threatened. But that ignores the fact that America has been shaped by successive waves of immigration going all the way back to the Pilgrims, and to the first African slaves. The country has proved that inclusiveness, adaptability and change are the keys to unparalleled success. Why on earth pull up the drawbridge now?

Maybe the real fear is more visceral than that. Maybe it’s that you don’t have to extrapolate immigration and fertility rates very far into the future to see an America in which minorities – Hispanic-, African- and Asian-Americans – are a majority. To put it another way: an America in which whites join the rest of us as just another minority. That’s already the case in our two most populous states, California and Texas, according to the Census Bureau, with others including New York, Arizona and Florida likely to follow soon.

Don’t freak out, folks. It’s not the end of the world. You might ask your black neighbors for advice on how to cope.

Eugene Robinson is a Washington Post columnist. Contact him by writing to eugenerobinson@washpost.com.