A major public expense. (M. Spencer Green/AP Photo)

It turns out that gun violence isn't just a public safety issue—it's also extremely expensive for taxpayers.

The total national hospital costs associated with firearm assault injuries ballooned to almost $700 million in 2010, according to a new analysis by The Urban Institute. And the bulk of those costs—almost three-quarters of them, to be more precise—aren't being paid for by the perpetrators, victims, or insurance companies, but rather by the American public.

"Most of this cost is paid for by the public, either through public insurance programs such as Medicaid or as uncompensated care for the uninsured," the Institute said in its report. "In a time of restricted public resources, these findings suggest that significant public resources could be saved or redirected if effective gun-violence prevention strategies could be identified."

The costs, both publicly funded and not, vary considerably by state. Within the six geographically and demographically different states singled out as part of the Institute's analysis—Arizona, California, Maryland, North Carolina, New Jersey, and Wisconsin—the hospital costs for firearm assaults ranged from just under $4 million in Wisconsin in 2010, to nearly $90 million in California that same year. Nationwide, the total hospital costs from gun assault injuries amounted to $670 million.

But the percentage of those costs that are paid for by the public was consistently high. In Arizona, 85 percent of hospital costs from firearm-assault injuries were publicly insured or not insured at all; while in California, where the percentage was lowest, 65 percent of such costs were still publicly insured or uninsured. Nationally, the 73 percent were publicly insured or uninsured.

"The purpose of this study was to dive into six rather different states and see if the pattern was there in all of those very diverse states," said Embry Howell, a senior Health Policy fellow at The Urban Institute. "And it was. While there's a range, it's actually a pretty tight range. Most of the costs are coming straight out of state Medicaid budgets, or even local hospital budgets."

The analysis also found that gun assault injuries are disproportionately concentrated among young males—young men aged 15 to 34 accounted for 70 percent of such injuries. And young black males are the largest victims; in each of the six states surveyed, black males had the highest rate of firearm assault injury.

As the number of gun stores continues to grow nationwide, and evidence continues to surface that more guns might not actually lead to less crime—or hospital visits, for that matter—it's important to bear in mind that the costs of gun violence aren't merely a burden on those directly afflicted, but also the wider public.

It's also worth remembering that the total costs of gun violence extend well beyond the price of associated hospital visits. The total cost of gun violence, which includes the societal cost, has been estimated at more than $170 billion annually. "A lot of costs aren't even included in this, like the costs after people leave the hospital," Howell said. "Basically, you're paying for them, even if indirectly."