A new study aimed at figuring out who owns gun in the United States and why suggests that about a third of Americans have at least one.
Most are white males over the age of 55, and a "gun culture" is closely linked with ownership, the team at Columbia University reports.
The study, published in the journal Injury Prevention, is one of several trying to pin down the number of gun owners in the United States. No agency keeps statistics on gun ownership and many pro-gun activists advocate keeping gun ownership private because of fears about potential future laws that might take guns away.
Bindu Kalesan, an assistant professor of epidemiology at Columbia, and colleagues surveyed 4,000 people. They asked them if they owned guns and also asked about attitudes toward gun ownership.
"One-third of Americans reported owning a gun, ranging from 5.2 percent in Delaware to 61.7 percent in Alaska," they wrote in their report. "Gun ownership was 2.25 times greater among those reporting social gun culture than those who did not," they added.
In the Northeast, gun ownership rates ranged from 5.8 percent in Rhode Island to 28.8 percent in Vermont.
In the Midwest, rates ranged from 19.6 percent in Ohio to 47.9 percent in North Dakota. In the South and mid-Atlantic, rates ranged from 5.2 percent in Delaware to 57.9 percent in Arkansas. And in the West, California had the lowest rate of gun ownership at 20 percent, while nearly 62 percent of Alaskans said they had a gun.
It's not clear which comes first, a pro-gun culture or owning guns, they added. "Social gun culture was measured using four questions that assessed whether an individual's 'social circle thinks less of them if they did not own a gun', 'family thinks less of them not owning a gun', 'social life with family involves guns' and 'social life with friends involves guns'," they explained.
"In conclusion, we found (a) strong association between social gun culture and gun ownership. Gun cultures may need to be considered for public health strategies that aim to change gun ownership in the USA."
Many doctors and public health experts argue that gun ownership is a health question. It's not a popular view in the U.S., with powerful support for the right for individuals to have weapons. But groups such as the American Academy of Pediatrics have been speaking up, and the Obama administration has directed the Centers for Disease Control and Prevention to research gun injuries.
The pediatrics academy highlighted a report last year that showed 500 American children and teenagers die in hospitals every year from gunshot wounds, and other studies show suicide rates go up with access to guns.
And a controversial study released earlier this month by the Violence Policy Center used FBI data to show that 259 people used a gun to kill someone else in self-defense in 2012, compared to 8,342 criminal homicides involving a gun.
"Firearm violence in the USA continues to be a major public health concern," Kalesan's team wrote. "There is little question that the high prevalence of gun ownership in the USA contributes to the burden of firearm-related injury."
Different surveys find different rates of gun ownership.
The latest General Social Survey found that 32 percent of Americans either own a firearm themselves or live with someone who does.