We’re seeing it here in Brooklyn, and it’s happening everywhere: ethnic parishes, built by the blood, sweat and tears of Slavs, Italians, Poles and Germans, are rapidly disappearing. Immigrants are moving to the suburbs, and their children are scattering.

Here’s a glimpse at what that means for the industrial area of Allentown, Pennsylvania:

It’s Polish Heritage Day at St. Kunegunda, the halupkies and sausages are simmering in the basement social hall and the Golden Tones Polka Band is tuning up in the choir loft, ready to inject some accordion-and-trumpet rhythms into the standing-room-only Saturday evening Mass.

Parishioners at this church in the northern Schuylkill County borough of McAdoo call it a polka Mass, though that’s an informal and somewhat misleading term. The waltz-like music may summon the spirit of an old-time village dance, but the hymns — some in English, some in Polish — are sacred, and the liturgy unfolds along traditional lines.

It’s as distinctly ethnic as anything you’ll find in this corner of coal country, where — defiant of time and change and suburbanization — Catholic parishes identified by ethnicity have persisted, far removed from their immigrant roots but adhering as best they can to Old World identities.

But the age of the ethnic church in the coal regions and across the Allentown Catholic Diocese may be passing. An institution struggling to fill pews and vocations can’t afford to maintain separate buildings just blocks — sometimes doors — apart. So consolidation, the process that has consumed churches in Pittsburgh, Philadelphia, Boston and countless other places in recent decades, seems poised to claim at least a few parishes here.

The diocese has embarked on a long-term study of parishes almost certain to result in closings and consolidations across its five counties. According to criteria released Friday, the diocese wants pastors to oversee only one parish each (some today are in charge of as many as four) and aims to make the priest-to-parishioner ratio 1 to 2,400.

Because of their prevalence, proximity and declining membership, ethnic parishes, also called national parishes, may be especially vulnerable to consolidation. And that means coal country could be especially hard hit. Of the 59 ethnic churches in the diocese, 30 are in Schuylkill County, a concentration that reflects the way Europeans settled in this region in the 19th and 20th centuries. Poles, Germans, Slovaks, Italians — all have their own churches, holdovers from the days when the institutional church provided newcomers with enclaves where they could worship in their own tongues and traditions even as they learned new ones.

Consider Mahanoy City: It covers half a square mile and has six Catholic churches founded to serve, among others, Germans, Italians, Poles and Lithuanians. That wasn’t unreasonable in 1920, when the population was 15,600. But only about 4,400 people live in the borough today. Likewise, McAdoo’s population has shrunk from 5,200 in 1940 to about 2,200 today. And in both places, as across the nation, Mass attendance is far lower today than in those long-ago boom times.

Historically, consolidation has virtually guaranteed hard feelings among the faithful. More than a decade ago, former Pittsburgh Bishop Donald Wuerl was accused of ”ethnic cleansing” by aggrieved parishioners. When consolidation hit Boston, some of the faithful occupied churches for days or even weeks in protest.

”It’s a traumatic thing when they have to give up the building,” said Mary L. Gautier, senior research associate with the Center for Applied Research in the Apostolate. The center, affiliated with Georgetown University in Washington, D.C., conducts sociological studies about the Catholic church.

”It’s like a death,” Gautier said. ”It’s giving up something and it’s painful.”

The diocese, for its part, won’t make any predictions about closings. The process began only recently and won’t bear fruit until at least spring, spokesman Matt Kerr said Friday.

In McAdoo, at least, the people who have kept the churches going — grandsons and granddaughters of off-the-boat miners, railroaders and seamstresses — seem resigned to the coming changes. But they predict ethnic identities will persist even if ethnic parishes are cobbled together into new parishes that must, according to the diocese rules, choose a new, nonethnic name.

”They’re not tied to a building,” the Rev. Edward Zemanik says of the parishioners at St. Kunegunda and the three other McAdoo-area parishes he oversees: St. Mary of the Assumption (Slovak), Immaculate Conception (Italian) and St. Patrick (technically a ”territorial” parish of general membership but rooted in the shamrock soil). That adds up to about 2,100 parishioners.

Some of the cultural distinctions from the old days are already long gone. For example, people are less likely to view the union of a bride from St. Patrick’s and a groom from St. Kunegunda’s as a ”mixed marriage.”

”We’re all together anymore,” said Franklin Minor, 67, a parishioner from the Italian flock of Immaculate Conception mingling happily among the patrons of St. Kunegunda’s heritage dinner.

”You’ve got to respect and honor everyone else’s traditions and don’t forget your own,” added Ron Meleski, 55, tending bar as the Golden Tones tuned up for the post-dinner dance. ”But we’re all Americans, too.”

Even so, said Zemanik, a Slovak immigrant’s grandson, ”don’t try to tell these people they aren’t Slovak, aren’t Polish, aren’t Italian.”

Read on for some history behind all this. My Slovak grandparents, I’m sure, would be crushed at what is happening. A way of life is disappearing — and with it, an important link to the past.

Msgr. Edward Zemanik pastor at St. Kunegunda blesses a child during mass at St. Kuneguda Church in McAdoo, Pa. By: Jane Therese, Allentown Morning Call.