BALTIMORE — New York City is building a new database to track guns used in crimes, and it intends to share the information with police departments up and down the East Coast in an effort to crack down on illegal gun trafficking.

The regional database would contain gun trace data recently released by the federal Bureau of Alcohol, Tobacco, Firearms, and Explosives, as well as ballistics information about guns used in crimes and intelligence gathered during investigations of gun offenders.

Mayor Bloomberg teamed up with the mayor of Baltimore, Sheila Dixon, to launch the effort. Baltimore is planning to build and launch a gun database of its own within the next few months, Ms. Dixon said. It would become part of the East Coast system.

Mr. Bloomberg said the shared database would attempt to bring together cities along Interstate 95, which he said is a central gun trafficking route, to try to cut off the gun trade.

“A system of regional data sharing has the potential to fundamentally alter the battlefield in the war against interstate gun trafficking,” Mr. Bloomberg said yesterday, speaking at Baltimore City Hall before attending a summit on gun violence organized by the group he co-founded, Mayors Against Illegal Guns. “Right now cities are fighting largely in isolation. With a regional data sharing system we will be able to communicate with one another far more consistently and effectively.”

He said the federal government should be building a national system to track illegal guns, but added that because it isn’t doing so, cities are doing it on their own. The federal government had been keeping a lock on most of its gun trace data, Mr. Bloomberg said, but agreed last year to release some of the data after Mr. Bloomberg and other mayors in his coalition made public calls for it to be shared more freely.

A spokesman for the National Rifle Association, Andrew Arulanandam, said there is no need for additional gun databases and said Mr. Bloomberg should spend his time and resources fighting crime instead of holding press conferences.

Considered by some to be a potential presidential candidate, Mr. Bloomberg noted yesterday that 34 Americans are killed by guns every day and argued that the presidential candidates should be talking about gun deaths.

Although some political observers say Mr. Bloomberg’s stance on guns will cost him votes in the South and the West if he runs for president, the mayor said he considers taking a strong stance on guns to be “a vote getter rather than a vote loser.”

“I would want to vote for somebody that said concretely how they would improve the safety on our streets and I wouldn’t want to vote for somebody that is just ducking the issue,” he said.

Mr. Bloomberg also disclosed yesterday that he is a member of the National Rifle Association. A membership card with his name on it arrived about four weeks ago. He said he doesn’t know who signed him up for it.

Mr. Arulanandam of the NRA said he suspected he knew who was behind the membership.

“It was likely his campaign manager, upon realizing that the graveyard of presidential hopefuls is filled with people who supported gun control,” he said.