The number of Americans carrying loaded handguns doubled between 2015 and 2019, according to a national study that surveyed adults living in homes with firearms across the US.

"Between increases in the number of people who own handguns and the number of people who carry every day, there has been a striking increase in handgun carrying in the US," says University of Washington epidemiologist Ali Rowhani-Rahbar, who led the study.

The United States has the most civilian-held firearms of any country in the world. A slew of epidemiological studies on firearm violence in the US have evidenced how guns cause immeasurable harm.

But only a handful of peer-reviewed national surveys on the gun-carrying behaviors of firearm owners have been completed in the past 30 years – making this new data a significant resource in monitoring changes in the nation's attitudes towards firearms.

To understand how often firearm owners carry a handgun and why, and differences between states with more or less restrictive laws on carrying weapons, the researchers surveyed nearly 2,400 American adults living in households with firearms.

Based on the study's findings, the team estimates that 6 million handgun owners carried a handgun on their person every day in 2019 – twice as many as the 3 million who carried daily in 2015, when the last national firearms survey was completed.

This was before the pandemic when gun violence surged in the US as psychological, economic, and social stressors escalated, putting further strain on an already overloaded health system.

"We found that about 3 in 10 handgun owners carried a loaded handgun on their person in the past 30 days; among those, about 4 in 10 did so every day," Rowhani-Rahbar and colleagues write in their paper, published in the American Journal of Public Health.

Among the nationally representative sample of 2,389 handgun owners, the majority who reported carrying a firearm were white, male, and aged 18–44.

Personal protection is now the main reason why roughly three-quarters of firearm owners reported carrying a loaded handgun, the study found, up from 46 percent who cited it as a primary reason in 1994.

While security is a rising incentive, the possession of more guns doesn't make individuals any safer in reality, according to research. Past studies conclude the introduction of stricter gun control laws has saved lives in countries around the world. In spite of this, the increasing prevalence of handguns in the US coincides with a marked relaxation in legislation.

"These trends have been accompanied by a loosening of state laws governing who can carry handguns in public places," the researchers write. Where in 1990 only one state in the US allowed people to carry a loaded handgun on their person without a permit, now 21 states do.

At the same time, the proportion of US firearm owners who receive formal firearm training – most commonly on safe handling, safe storage, and preventing accidents, but little in the way of suicide prevention – has not meaningfully changed over the past two decades.

The latest study suggests firearm-carrying behavior may at least be somewhat responsive to the types of laws governing carrying in public places.

Proportionally fewer firearm owners carried handguns in states where issuing authorities had substantial discretion in granting permits: one-fifth of owners did so in those states in the previous month compared to one-third of handgun owners residing in states where no permit is required to carry a loaded firearm.

However, the study also found a substantial increase between 2015 and 2019 in the number of handgun owners who carried handguns without a permit when they were legally required to have one – a figure now hovering between 7.5 and 11.5 percent of handgun owners surveyed.

A number of respondents also admitted they didn't know if they held a permit or not. Some refused to answer questions about permits, days they carried firearms, or the types of guns they owned.

The findings come after a recent US Supreme Court ruling struck down a 109-year-old New York state handgun-carrying law, which has already seen state laws loosen in other parts of the country.

"In light of that ruling, our study reinforces the importance of studying the implications of handgun carrying for public health and public safety," Rowhani-Rahbar says.

Gun violence and firearm-related deaths are largely preventable, making it a public health issue that in particular steals young people's right to health, life, and safety.

In 2020, firearm-related injury became the leading cause of death in the US among adolescents and infants aged 1 to 19 years, surpassing motor vehicle crashes, cancerous tumors, and drug overdose and poisoning.

While mass shootings continue to haunt the United States, most firearm-related deaths are caused by suicide, homicide, or unintentional fatal injuries.

Around half of Americans wish gun laws in their country would be made more strict. Previous global analyses show, however, that nothing less than a major overhaul of legislation is required to see significant change.

The study was published in the American Journal of Public Health.