CHICAGO – The county that includes Chicago on Friday approved a tax on firearms to help pay the healthcare costs from gun violence, the first major U.S. metropolitan area to impose such a tax as a form of gun control.

Under the plan, Cook County, Illinois, will impose a $25 tax on each firearm sold. The tax is expected to raise $600,000 in revenue in 2013.

With Friday’s vote, the nation’s third most populous county with nearly 5.2 million residents becomes the first major U.S. metropolitan area to impose a tax as a form of gun control, according to the Law Center to Prevent Gun Violence.

The Cook County board of commissioners voted 9 to 7 to approve the firearms tax.

Cook County Board President Toni Preckwinkle, who proposed the handgun tax, had earlier this week abandoned an additional proposed tax of 5 cents a bullet because the tax in some cases would have exceeded the price of ammunition.

Preckwinkle said that 670 victims of gun violence had been treated by the county’s health system last year. The average cost per patient was $52,000.

There have been 443 murders in Chicago so far this year, surpassing last year’s total of 435 and 22 percent more than in the same period a year ago, according to Chicago police.

Taxes on buyers or sellers of guns or ammunition have been proposed but failed in six states, including California, Louisiana, Massachusetts, New Jersey, Oklahoma and Pennsylvania, according to the Law Center to Prevent Gun Violence.

Tennessee has a hunting-related 10-cent tax on sealed packages of shotgun shells and cartridges that applies to sellers. The money is used to support wildlife resources.

Richard Pearson, executive director of the Illinois State Rifle Association, has called the Cook County proposal another scheme to punish law-abiding firearm owners and dealers. He said it would prompt people to purchase weapons elsewhere.

(Editing by Greg McCune and Andrew Hay)