Portside

The share of American households with guns has declined over the past four decades, a national survey shows, with some of the most surprising drops in the South and the Western mountain states, where guns are deeply embedded in the culture.

The gun ownership rate has fallen across a broad cross section of households since the early 1970s, according to data from the General Social Survey, a public opinion survey conducted every two years that asks a sample of American adults if they have guns at home, among other questions.

The rate has dropped in cities large and small, in suburbs and rural areas and in all regions of the country. It has fallen among households with children, and among those without. It has declined for households that say they are very happy, and for those that say they are not. It is down among churchgoers and those who never sit in pews.

The household gun ownership rate has fallen from an average of 50 percent in the 1970s to 49 percent in the 1980s, 43 percent in the 1990s and 35 percent in the 2000s, according to the survey data, analyzed by The New York Times.

In 2012, the share of American households with guns was 34 percent, according to survey results released on Thursday. Researchers said the difference compared with 2010, when the rate was 32 percent, was not statistically significant.

The findings contrast with the impression left by a flurry of news reports about people rushing to buy guns and clearing shop shelves of assault rifles after the massacre last year at an elementary school in Newtown, Conn.

“There are all these claims that gun ownership is going through the roof,” said Daniel Webster, the director of the Johns Hopkins Center for Gun Policy and Research. “But I suspect the increase in gun sales has been limited mostly to current gun owners. The most reputable surveys show a decline over time in the share of households with guns.”

That decline, which has been studied by researchers for years but is relatively unknown among the general public, suggests that even as the conversation on guns remains contentious, a broad shift away from gun ownership is under way in a growing number of American homes. It also raises questions about the future politics of gun control. Will efforts to regulate guns eventually meet with less resistance if they are increasingly concentrated in fewer hands — or more resistance?

Detailed data on gun ownership is scarce. Though some states reported household gun ownership rates in the 1990s, it was not until the early 2000s that questions on the presence of guns at home were asked on a broad federal public health survey of several hundred thousand people, making it possible to see the rates in all states.

But by the mid-2000s, the federal government stopped asking the questions, leaving researchers to rely on much smaller surveys, like the General Social Survey, which is conducted by NORC, a research center at the University of Chicago.

Measuring the level of gun ownership can be a vexing problem, with various recent national polls reporting rates between 35 percent and 52 percent. Responses can vary because the survey designs and the wording of questions differ.

But researchers say the survey done by the center at the University of Chicago is crucial because it has consistently tracked gun ownership since 1973, asking if respondents “happen to have in your home (or garage) any guns or revolvers.”

The center’s 2012 survey, conducted mostly in person but also by phone, involved interviews with about 2,000 people from March to September and had a margin of sampling error of plus or minus three percentage points.

Gallup, which asks a similar question but has a different survey design, shows a higher ownership rate and a more moderate decrease. No national survey tracks the number of guns within households.

Andrew Arulanandam, a spokesman for the National Rifle Association, said he was skeptical that there had been a decline in household ownership. He pointed to reports of increased gun sales, to long waits for gun safety training classes and to the growing number of background checks, which have surged since the late 1990s, as evidence that ownership is rising.

“I’m sure there are a lot of people who would love to make the case that there are fewer gun owners in this country, but the stories we’ve been hearing and the data we’ve been seeing simply don’t support that,” he said.

Tom W. Smith, the director of the General Social Survey, which is financed by the National Science Foundation, said he was confident in the trend. It lines up, he said, with two evolving patterns in American life: the decline of hunting and a sharp drop in violent crime, which has made the argument for self-protection much less urgent.

According to an analysis of the survey, only a quarter of men in 2012 said they hunted, compared with about 40 percent when the question was asked in 1977.

Mr. Smith acknowledged the rise in background checks, but said it was impossible to tell how many were for new gun owners. The checks are reported as one total that includes, for example, people buying their second or third gun, as well as those renewing concealed carry permits.

“If there was a national registry that recorded all firearm purchases, we’d have a full picture,” he said. “But there’s not, so we’ve got to put together pieces.”

The survey does not ask about the legality of guns in the home. Illegal guns are a factor in some areas but represent a very small fraction of ownership in the country, said Aaron Karp, an expert on gun policy at the Small Arms Survey in Geneva and at Old Dominion University in Norfolk, Va. He said estimates of the total number of guns in the United States ranged from 280 million to 320 million.

The geographic patterns were some of the most surprising in the General Social Survey, researchers said. Gun ownership in both the South and the mountain region, which includes states like Montana, New Mexico and Wyoming, dropped to less than 40 percent of households this decade, down from 65 percent in the 1970s. The Northeast, where the household ownership rate is lowest, changed the least, at 22 percent this decade, compared with 29 percent in the 1970s.

Age groups presented another twist. While household ownership of guns among elderly Americans remained virtually unchanged from the 1970s to this decade at about 43 percent, ownership among young Americans plummeted. Household gun ownership among Americans under the age of 30 fell to 23 percent this decade from 47 percent in the 1970s. The survey showed a similar decline for Americans ages 30 to 44.

As for politics, the survey showed a steep drop in household gun ownership among Democrats and independents, and a very slight decline among Republicans. But the new data suggest a reversal among Republicans, with 51 percent since 2008 saying they have a gun in their home, up from 47 percent in surveys taken from 2000 through 2006. This leaves the Republican rate a bit below where it was in the 1970s, while ownership for Democrats is nearly half of what it was in that decade.

Researchers offered different theories for these trends.

Many Americans were introduced to guns through military service, which involved a large part of the population in the Vietnam War era, Dr. Webster said. Now that the Army is volunteer and a small fraction of the population, it is less a gateway for gun ownership, he said.

Urbanization also helped drive the decline. Rural areas, where gun ownership is the highest, are now home to about 17 percent of Americans, down from 27 percent in the 1970s. According to the survey, just 23 percent of households in cities owned guns in the 2000s, compared with 56 percent of households in rural areas. That was down from 70 percent of rural households in the 1970s.

The country’s changing demographics may also play a role. While the rate of gun ownership among women has remained relatively constant over the years at about 10 percent, which is less than one-third of the rate among men today, more women are heading households without men, another possible contributor to the decline in household gun ownership. Women living in households where there were guns that were not their own declined to a fifth in 2012 down from a third in 1980.

The increase of Hispanics as a share of the American population is also probably having an effect, as they are far less likely to own guns. In the survey results since 2000, about 14 percent of Hispanics reported having a gun in their house.