Washington ? The nation’s murder rate declined last year for the first time in four years, dropping to the lowest level in 40 years. Experts said local rather than national trends were mostly responsible.

The rates for all seven major crimes were down and the overall violent crime rate reached a 30-year low, according to the FBI’s annual compilation of crimes reported to the police.

There were 391 fewer murders nationwide in 2004 than the year before. The total of 16,137 worked out to 5.5 murders for every 100,000 people.

That’s a decline of 3.3 percent from 2003 and the lowest murder rate since 1965, when it was 5.1.

“The declines are relatively small compared to larger, steady drops in the 1990s, and the results are by no means the same across the country,” said Professor Alfred Blumstein of Carnegie-Mellon University in Pittsburgh.

Blumstein said Chicago with a decline of 150 murders and Washington, D.C., with a decline of 50 accounted for 51 percent of the net nationwide drop. St. Louis, on the other hand, saw an increase of 39 murders.

Of 19 large cities with more than 100 murders apiece in 2003, 13 had declines in 2004 while six recorded increases, Blumstein said.

“Most of these changes result from local conditions or random variation,” said Professor James Alan Fox of Northeastern University in Boston.

The four major violent crimes – murder, rape, robbery and aggravated assaults – declined from 1.38 million in 2003 to 1.37 million in 2004. That produced a 2.2 percent drop in the violent crime rate to 465.5 crimes per 100,000 people – the lowest since 1974, when it was 461.1.

The three major property crimes – burglary, auto theft and larceny-theft – declined from 10.42 million to 10.33 million in 2004. That pulled the property crime rate down 2.1 percent to 3,517.1 crimes per 100,000 people. These crimes produced an estimated loss of $16.1 billion, down 5 percent from 2003.

Rape was the only one of the seven crimes to show a numerical increase, up 0.8 percent to 94,635 offenses, but the rate of rape declined 0.2 percent to 32.2 per 100,000 people. Lynn Parish of the Rape, Abuse & Incest Network, a national anti-sexual assault group, said Justice Department studies show the incidence of rape, whether reported to police or not, has been declining over 30 years while the reporting of rape to police has climbed for a decade.

The FBI data were compiled from reports to more than 17,000 law enforcement agencies, representing 94.2 percent of the nation’s population.