If church attendance is any indication, Americans are as religious as they were 30 years ago. But the makeup of the nation's congregations has undergone significant changes during that same stretch, according to a study published in Sociology of Religion.

The findings challenge the popular notion that church attendance has decreased. Aside from a moderate decline in the 1990s, the study shows that Americans' churchgoing routines have been fairly constant over the decades, at around 23 to 28 services a year.

"There is a small decline in church attendance over time, but not nearly as large as suggested in popular culture, or even by some social scientists," said University of Nebraska-Lincoln sociologist Philip Schwadel.

The study also found that sizable shifts have occurred within traditionally reliable churchgoing groups – women, southerners and Catholics – that suggest those groups' overall impact on church attendance rates in the United States has begun to wane.

Researchers examined General Social Survey responses from nearly 41,000 Americans from 1972 to 2006. Using complete age, period and cohort data, they found that in 1972, Catholics attended religious services an average of 18 days per year more than mainline Protestants. By the first few years of the 21st century, however, the difference had dropped to about six days per year.

The estimated difference in attendance between southerners and non-southerners was almost six days per year in 1972. By 1996, the gap was just three days per year and has only slightly widened since then.

Women in 1972 went to church roughly 10 times more a year than men. By 2006, that gap had shrunk to about six more times a year.

The declining influence of women, Catholics and southerners is not the result of compositional changes, Schwadel said. In fact, the proportions of Catholics and those living in the South have risen in recent decades.

Instead, the researcher estimated that declining impacts of the traditional groups were related to rising education levels among all three, along with growing minority populations. Education levels rose disproportionately among women, Catholics and southerners in the last 35 years, leading to geographic and economic mobility that didn't broadly exist in the early 1970s.

The declining difference in attendance between Catholics and mainline Protestants does not necessarily mean all Catholics are attending less often. Instead, many Catholics now have high levels of church attendance because they are Latino, which make up one-third of American Catholics today, rather than because they are Catholic, the study found. In other words, the difference in attendance between non-Latino Catholics and mainline Protestants declining precipitously.

Women provide perhaps the most dynamic example of societal changes over the timespan, Schwadel said. Traditionally, they connected their roles in the home and the family to their roles in their churches.

"But as more women have gone to college, participated in the workforce and have begun to work outside the home, it can be said that they are becoming more like men in a number of ways," he said. "Few people have really thought about whether the traditional role of women in their church has changed. This may change that."

Men have historically held leadership positions in their congregations, while women have been the majority in the pews on any given Sunday, he said. More importantly, they have been the bedrock of most church organizations, powering the clubs and outreach groups.

Citation: Philip Schwadel, 'Age, Period, and Cohort Effects on U.S. Religious Service Attendance: The Declining Impact of Sex, Southern Residence, and Catholic Affiliation', Sociology of Religion, February 2010, 71: 2-24; doi:10.1093/socrel/srq005