WASHINGTON -- Even as Boston struggles against a tide of smuggled handguns, some state governments in the South are loosening their gun control laws in ways that critics say will make it easier for traffickers to bring illegal firearms into the Northeast.
Under pressure from the National Rifle Association, South Carolina abolished a state law last year that limited to one the number of handguns individuals can buy in a month, a measure that was designed in 1975 to prevent trafficking.
Virginia, which was the epicenter of gun smuggling into New York and Boston before it passed a one-gun-per-month law in 1993, weakened that rule in 2004 and gun control advocates fear that it could soon be abolished.
Academic studies have shown that limits on monthly gun purchases help limit smuggling, but lobbyists for gun manufacturers call such laws ''gun rationing" and say they infringe on Second Amendment gun ownership rights.
Over the past five years the overall trend on the state level has been toward lax gun laws, said David Hemenway, a professor at the Harvard School of Public Health who studies gun crime. That has left states such as Massachusetts and New York, which retain their strict gun limits, increasingly isolated.
When it is easy to buy firearms in neighboring states, Hemenway said, ''it just makes it a lot harder for states with less permissive gun laws to keep guns out."
Urban jurisdictions in the Northeast have some of the most restrictive gun ownership laws in the country, though shootings in Boston were up 11 percent from last year, according to statistics obtained by the Globe.
Police seized 490 guns in Boston through Aug. 23, up from 380 in the same period last year and 294 in 2001. A large percentage of those guns originated from outside the region.
Last month, a South Carolina judge sentenced a Boston man to 24 years in federal prison for buying 21 guns in the state, which he resold illegally in Boston after removing their serial numbers.
Sergeant Thomas Sexton, a spokesman for the Boston Police Department, said the police were concerned that less restrictive gun laws in other states would fuel smuggling into the region.
''It is a concern that some of these other states are relaxing some of their gun laws," he said.
South Carolina Governor Mark Sanford, a Democrat, signed legislation ending that state's ban in May 2004. In Virginia, Democratic Governor Mark Warner, who may seek the party's 2008 presidential nomination, approved an exemption for gun owners with ''right-to-carry" permits from the state's one-gun-a-month limit.
Pinpointing the precise source of guns smuggled into the Northeast is difficult, analysts say, because last year Congress inserted a provision into a spending bill that prevented the US Bureau of Alcohol, Tobacco, Firearms, and Explosives from releasing federal data about where guns used in violent crimes originated.
The amendment, sponsored by US Representative Todd Tiahrt, a Kansas Republican, prohibited the ATF from releasing documents related to ''traces" of guns. Local authorities can request traces for individual firearms to locate the owner of a stolen gun or in criminal investigations, but they don't have access to traces requested by other agencies.
As part of an ongoing lawsuit, the city of New York has subpoenaed the ATF over access to trace data, which New York police hope to use to identify rogue gun dealers.
Lawyers from the city sought trace reports to establish that many guns used to commit crimes come from the same sources.
A federal judge has ruled in favor of the city twice, but the ATF is still seeking to avoid turning over the traces.
In 1999, when the ATF last made some data from gun traces available, the report showed that Florida was the top source of handguns used by youth criminals in Massachusetts in 1997-98, accounting for 17.6 percent of crime. By comparison, only 14.7 percent of guns came from in-state.
Virginia, North Carolina, and Florida were the top three sources of crime guns for young people in New York City.
Brian Malte, outreach director of the Brady Campaign to Prevent Gun Violence, an antigun group, said that while the repeal of gun control laws was worrying, another problem is the many states that lack strong gun control laws to begin with.
''It's not like a South Carolina, that they've passed and then repealed the law," he said.
''They just never had the laws to begin with."