The most notable Catholic-related trend in the new American Religious Identification Survey (ARIS) survey of American religion is geographic.

Driven primarily by Hispanic immigration, a shift is taking place in the Catholic population from the U.S. Northeast to the Southwest states where Latin American immigrants are concentrated.

The ARIS survey was conducted by Trinity College’s Program on Public Values.

This is what the ARIS survey says, in its introductory “Highlights” section:

“America’s religious geography has been transformed since 1990. Religious switching along with Hispanic immigration has significantly changed the religious profile of some states and regions. Between 1990 and 2008, the Catholic population proportion of the New England states fell from 50% to 36% and in New York it fell from 44% to 37%, while it rose in California from 29% to 37% and in Texas from 23% to 32%.”

The decline in religion in the Northeast isn’t exclusively a Catholic phenomenon, by any means. The report also notes that the northern New England states now have the dubious distinction of being the most irreligious area of the United States, displacing the Pacific Northwest.

But because the Northeast has been so central to Catholic identity in America since the first waves of immigrants from Ireland, Italy and other predominantly Catholic countries began flooding to the country’s shores, the ARIS survey understandably regards the decline of Catholic affiliation in that region to be particularly significant.

“The decline of Catholicism in the Northeast is nothing short of stunning,” Barry Kosmin, a principal investigator for the American Religious Identification Survey, said in the lead paragraph of a March 9 Trinity College press release about the ARIS survey. “Thanks to immigration and natural increase among Latinos, California now has a higher proportion of Catholics than New England.”

Another significant trend, and one that ought to be worrying to the Church in every region of the country, is the substantial decline between 1990 and 2008 of the percentage of Americans who identify themselves as Catholic in four major ethnic groups.

Among white non-Hispanics, the percentage of Catholics fell from 27% to 21%; among black non-Hispanics, from 9% to 6%; among Hispanics, from 66% to 59%; and among Asians, from 27% to 17%. However, the decline was sharper in the 1990s than in this decade for whites, blacks and Asians. And among Hispanics the percentage who identifies themselves as Catholic actually rose slightly from 57% in 2001 to the current 59%.

The reason the overall percentage of Catholics didn’t fall further in the total American population during the 1990-2008 period reflected the continuing influx of Latin American immigrants.

“If the Hispanic population, which is the most Catholic, had not expanded then the Catholic population share nationally would have significantly eroded,” the survey notes. “One feature of the white population today is in fact the large number of ex-Catholics, who are now found among the Nones and have helped that group grow.”