“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.