An estimated three million adult American handgun owners carry a loaded firearm on a daily basis, and nine million do so on a monthly basis, a study has found.
Vast majority cited protection as the primary reason for carrying a firearm.
The study is the first in over 20 years to scrutinise why, how often, and in what manner US adults carry loaded handguns.
It also examines how concealed handgun-carrying behaviour differs across states, depending on their laws.
"Carrying firearms in public places can have significant implications for public health and public safety," said Ali Rowhani-Rahbar, an associate professor at the University of Washington in the US.
"An important first step to examining the consequences of firearm carrying at the national level is an accurate measurement of the occurrence of this behaviour and characterisation of those who engage in it," said Rowhani- Rahbar, lead author at the American Journal of Public Health.
Compared with handgun owners who did not carry, those who did report carrying handguns tended to be younger, and more often male, live in the southern US, have grown up in firearm-owning households, self-identify as politically conservative, and own more than one type of firearm.
Researchers reviewed the handgun-carrying behaviour of 1,444 gun owners, using data from a 2015 nationally representative survey designed by Miller and Azrael.
"It was important to study handgun carrying because about 90 per cent of all firearm homicides and nonfatal firearm crimes for which the type of firearm is known are committed with a handgun," said Rowhani-Rahbar.
The study found that 80 per cent of surveyed handgun owners who carried their handgun had a concealed-carry permit, and 66 per cent said they always carried their handguns concealed, compared with 10 per cent who said they always carry their weapons openly.
When comparing handgun-carrying behaviour with corresponding states' laws, researchers found that proportionally fewer handgun owners carried a concealed handgun if they lived in a state whose laws afforded greater discretion to issuing agencies in the review of concealed- carry applications.
Some owners nevertheless reported carrying a concealed handgun without a permit in states in which doing so was illegal.
Rowhani-Rahbar said that more research is needed to comprehensively evaluate the impact of increasingly permissive firearm-carry laws.
Future studies should focus on analysing how different concealed-carry laws influence carrying, and characterising illegal carrying behaviour among those who have been denied permits.