What's Behind the Drop in US Murder Rate?

THE maturing of drug-trafficking gangsters is being given considerable credit for a 12 percent plunge in the number of murders during the first half of this year.

Experts also cite aggressive local police efforts aimed at drug gangs, the overall aging of the baby-boom generation, and even a cultural change in attitudes toward violence.

The decline in murder reported Sunday by the FBI is the largest drop in at least 35 years.

It was the most dramatic change in the FBI's preliminary figures for crimes reported to police during the first six months of this year, compared with the same period of 1994.

There was a 1 percent decrease in overall reported crimes and a 5 percent drop in violent crimes alone. The two declines were very similar to the reductions in those categories during all of 1994. Property crime remained unchanged.

''As drug markets have matured, just like Mafia markets matured years ago, they have found ways to settle disputes without so much lethal violence,'' said Alfred Blumstein, a professor at Carnegie Mellon University in Pittsburgh. Homicides had soared in the 1980s as drug traffickers warred over turf and recruited teenagers into their gangs.

Like last year, the biggest drops came in the largest cities - those with more than 1 million residents - where overall crime declined 6 percent in the first half of this year. Suburban areas showed no change overall, and rural areas recorded a 3 percent increase in overall crime.