The Washington PostDemocracy Dies in Darkness

New study shows dramatic gap in religious diversity between the Southeast and much of the country

Hundreds gather at the steps of the Lincoln Memorial in Washington, D.C., April 21, 2019, to celebrate the 41st annual Easter sunrise service. (Astrid Riecken for The Washington Post)

A new sweeping religion survey of nearly half a million Americans shows some regions of the country remain religiously homogenous — especially the Southeast — and charts the growing political influence of the religiously unaffiliated, whose presence has more than doubled in both major parties in recent years.

Public Religion Research Institute analyzed data on interviews with more than 500,000 Americans from 2013 to 2019, and combined it with data from the U.S. Census Bureau on 3,142 counties across the country. The project offers a picture of the religious demographics of every county, including Maryland’s Montgomery and Howard counties, which rank in the top 10 most-diverse.

The survey and analysis digs deep into the big-picture story of American religion: Dramatic change in the past 20 years, especially the shrinking of the White Christian population and the growth of religiously unaffiliated Americans. PRRI says those two trends appear to be slowing in the last couple years , but CEO Robert Jones says it is too early to know if it’s more like a pause.

White Christians have gone, as a proportion of the U.S. population, from 65 percent in 1996 to 42 percent in 2018. PRRI found that the number ticked up in 2019 and 2020 to 44 percent. Other major pollsters found slightly different numbers, with Pew Research saying it was 40 percent in 2020.

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Past trends are not guaranteed to continue, Jones said. “These are expressions of broad social changes in the country, and we don’t know what kind of upheavals will shift things. The news here is that these trends we’ve been watching, [which] looked the same for a decade, [now] look slightly different.”

Looking at young Americans, some trend lines appear to be moving in one direction. Last year, 36 percent of Americans aged 18-29 told PRRI they have no religious affiliation, compared with 23 percent of that same age group in 2006 and 10 percent in 1986.

Twenty-three percent of all Americans say they are unaffiliated, PRRI found. However, for 20 years, as the unaffiliated population began to increase, estimates of its size by different polling outfits have varied by as much as 10 percentage points. Gallup found those who are unaffiliated were about 20 percent of the adult population in 2020, while Pew Research estimates the figure is 28 percent.

The PRRI survey found the unaffiliated are becoming a much larger part of both parties, the Democrats in particular. Between 2006 and 2020, the percent of Republicans who say they are unaffiliated went from 4 to 13 percent. The percent of Democrats went from 9 to 23 percent.

A book out this year by three well-known political scientists called “The Secular Surge” seeks to advance the years-long discussion about the non-religious and their growing political influence. The book, by John Green, Geoffrey Layman and David Campbell, identifies the boom in Americans who are decidedly secular in their outlook, not just unaffiliated. These are people who are “guided by their understanding of the observable, natural world,” and committed to “science and objective evidence.”

One in four Americans are secularists, the authors’ research finds, and the movement is growing among the young. Chapters of the Secular Student Alliance went from 42 in 2003 to hundreds today, the book says, reflecting organizing and political mobilizing. The book argues that the core divides in the Democratic Party — between progressives and centrists, highly evident in the 2020 presidential race — has secularism “at the very heart of such battles for the soul of the Democratic Party.”

In other words, unaffiliated and secular Americans are growing in both parties, but especially so on the Democratic side, creating an important fault line, the authors argue, with core Black and Latino constituencies. Secular voters generally are more progressive, including on issues like defense spending, the desire for free college education and exemptions from anti-discrimination laws for religious people and businesses.

The PRRI study offers a unique look at the religious composition of each county by different metrics, including overall diversity and how much of each county is made up of groups such as Latino Catholics, Latter-day Saints members, and others. It uses darker and lighter blues to signify the presence of a pattern.

The map shows increased overall diversity in the West, Midwest, Northeast and in various spots across the country, especially in and around cities. The Southeast quadrant is especially light on diversity.

“What’s remarkable is you can see the cultural history of the country in these maps,” said Jones, noting religious settlement patterns that endure. “You can still see the history of the Civil War, with White evangelicals still concentrated in the Southeast, White non-evangelicals in the Upper Midwest and Northeast. You can still see that North-South divide.”

Hispanic Catholics are concentrated in the South, Southwest and South Florida, while Muslims are scattered in small clusters around the country.

Polling Director Scott Clement contributed to this report.