Nearly one in every three Americans owns a gun, according to a recently published study in the journal Injury Prevention by researchers Bindu Kalesan, Marcos Villarreal, and Katherine Keyes of Columbia University, and Sandro Galea of Boston University.

The researchers conducted the survey of 4,000 adults in an attempt to answer the question of how many Americans own a firearm — and why — amid a lack of overall data and statistics on gun ownership. They found a broad regional variation in gun ownership — from as low as near 5% in some areas to as much as 66% in others. In individual states, this ranged from 5.2% ownership in Delaware to 61.7% in Alaska.

Here's a map illustrating their results:

Business Insider/Andy Kiersz, data from Kalesan et. al., June 2015 The researchers discovered the variation was due to everything from local and state firearm laws to cultural and social norms. Those who reported the prevalence of a "social gun culture," in fact, were 2.25 times more likely to own a gun.