In the past two decades, Americans have added approximately 70 million firearms to their private arsenals. There are more gun owners, but they make up a slightly smaller share of the population. Handguns have surged in popularity, and the era of the super-owner is here: roughly half of all guns are concentrated in the hands of just three percent of American adults.

These are among the key findings of a sweeping new survey of gun ownership, provided in advance of publication to The Trace and The Guardian by researchers at Harvard and Northeastern universities. Our two news organizations are partnering to present a series of stories this week based on the survey.

There have been other evaluations of American gun ownership in recent years, but academics who study gun-owning patterns and behavior say the new survey is the most authoritative and statistically sound since one conducted in 1994 by Philip Cook, a researcher at Duke University.

“It’s a fundamental building block for gun research,” Cook says of the new Harvard/Northeastern survey. “And in a variety of ways, having this baseline information is going to inform research and policy development. It’s essential that we have accurate and up-to-date information.”

Roughly 100,000 Americans are injured by a gun every year, with a third of those incidents resulting in death. But research into the causes of the violence, methods of prevention, and its toll on families and communities is almost entirely conducted by academics and other private groups.

The Centers for Disease Control and Prevention, the government entity that studies other public health issues, virtually ignores gun violence, owing to legislation widely interpreted as preventing such research.

“What people do with their guns, who has them, how they obtain them — these are all these behaviors that are very relevant to gun violence,” says Daniel Webster, a gun violence researcher at Johns Hopkins University. “It’s rather insane that we don’t have our fingers on the pulse, and can’t answer basic questions without going back decades.”

Researchers say the strength of the new survey is its scope. Participants were asked to provide detailed information about their guns and their ownership habits — the types of firearms in their homes, how they are stored, and why they keep them.

“It’s very rare for other surveys to try to estimate the gun stock,” David Hemenway, the director of the Harvard Injury Control Research Center, and one of the lead authors of the survey, tells The Trace. “Other surveys ask ‘Is there a gun in the house,’ and not ‘How many guns?’”

The responses reveal a fundamental shift in gun-owning attitudes. Whereas most owners once considered their firearm primarily a hunting or sports shooting tool, a majority now say they keep guns to protect themselves, their families, and communities.

In 2004, the same group of Harvard and Northeastern researchers produced a similar survey of gun ownership, but the results were not as statistically sound as the new study, for reasons that also challenged other pollsters of the era. The previous study was conducted by telephone, but a sharp decline in landline usage in the early 2000s led to lower response rates among participants and weaker sample sizes. Deb Azrael, a Harvard researcher and a lead author on the study, says these factors may have artificially inflated the findings.

There have been other studies of gun ownership patterns since 2004, but none as comprehensive as the new effort. Pew Research, for example, published an analysis on the demographics and politics of gun-owning households in 2014, using data from a larger survey on American political views. The results provided the percentage of citizens with guns in their homes, but omitted specifics on how many guns each household owned, or the most common types of weapons.

The Harvard and Northeastern survey estimates that there are now 265 million firearms in private hands in the U.S.

The Trace and The Guardian were provided a summary of the survey’s findings. The survey does not draw conclusions about how changes in gun ownership could affect public health, though it will significantly inform subsequent examinations, the researchers say.

It was conducted using the GfK Knowledge Panel, a nationally representative online panel used by researchers and marketing companies to poll Americans on a variety of issues. It is undergoing peer-review, and a summary will be published by the Russell Sage Foundation next year.

[Photo: AP Photo/Danny Johnston]