My wife and I traveled to southern Italy this month to visit two tiny villages my mother's parents had migrated from more than a century ago. The villages -- Cerasi, a mountain retreat with stunning views high up in Calabria's Aspromonte range, and Laurenzana, a medieval hilltop gem in Basilicata -- have a fraction of the population they had when my grandparents left in the early 20th century, destined to meet and marry on crowded Mott Street in Manhattan.

They were swept up in one of history's great migrations. The same can be said for my wife Maureen's Irish ancestors. Visiting the villages reminded me of a trip we took several years ago to Gweedore on Ireland's rugged northwest shore. Maureen's great-grandmother left that very poor community in County Donegal for Brooklyn in the 19th century, and the area's many roofless and vacant stone huts testify that many others also migrated.

The Irish and Italian immigrants to New York had much in common despite differences in language and custom. They were people of the periphery who suffered from poverty and exploitive governance. They shared a religion in Catholicism, and work experience that consisted mostly of the heavy lifting needed for farm labor.

Book ExcerptThe Story of NY's Irish and ItaliansCartoonDavies' latest cartoon: At the employment office

Yet they clashed in New York. Construction sites, parish churches, union halls, the police station, the waterfront: All became arenas for Irish-Italian conflict in the late 19th century and well into the 20th century.

When the Italians arrived in large numbers in New York starting around 1880, the Irish were established. A sign of that success was the election of William R. Grace as the city's first Irish-Catholic mayor in 1880.

But many of the Irish remained impoverished and tempers flared when Italians competed for jobs as laborers, willing to work longer days for less money. The workers' fights became so common that the Brooklyn Eagle editorialized, "Can't they be separated?"

advertisement | advertise on newsday

With that rivalry in the background, even the church became an arena for conflict. Rather than try to unify the congregations, Irish-American pastors found it better to make the Italians worship in the church basement, stirring resentment and even some pointed words from the Vatican.

I had heard stories of the Irish-Italian rivalry growing up, but research in archives and 19th century news accounts showed it was more bitter than I had realized. Decades passed before it became possible for couples of Irish and Italian ancestry to marry with the warm assent of their respective tribes, as was the case when Maureen Collins and I wed in 1976 at St. Vincent de Paul Catholic Church in Elmont.

What changed? As both immigrant groups were accepted -- eventually -- into American society, they mingled as equals in schools, churches, sports leagues, workplaces, unions and veterans' groups and got to know each other better.

Sign up for The Point

Go inside New York politics.

They liked what they saw, and married each other in large numbers beginning in the years after World War II. Parishes, once the scene of much Irish-Italian rivalry, played an important role in this accord.

The growth of the suburbs and new residential sections of the city also helped to bring Irish and Italians together. People left the old ethnic bailiwicks and met as neighbors.

Politics played a role, too, if in an unfortunate way: The Irish and Italians drew together as the bulk of a "white Catholic" demographic often at odds with blacks and Latinos, who also migrated to escape poverty.

Ethnic and racial division persists -- but so does the hope that as people get to know each other, such boundaries will blur and fade.

Paul Moses is a professor at Brooklyn College/CUNY and former Newsday reporter. He is the author of "An Unlikely Union: The Love-Hate Story of New York's Irish and Italians."