Washington ? The nation’s crime rate last year held steady at the lowest levels since the government began surveying crime victims in 1973, the Justice Department reported Sunday.

The study was the latest contribution to a decade-long trend in which violent crime as measured by victim surveys has fallen by 55 percent and property crime by 49 percent. That has included a 14 percent drop in violent crime from 2000-2001 to 2002-2003.

“The rates are the lowest experienced in the last 30 years,” Justice Department statistician Shannan Catalona said in the report. “Crime rates have stabilized.”

Murder is not counted because the Bureau of Justice Statistics study is based on statements by crime victims. In a separate report based on preliminary police data, the FBI found a 1.3 percent increase in murders between 2002 and 2003 from 16,200 to about 16,420.

There are numerous possible explanations for the sharp, sustained decrease in crime. But experts say the fact that crime rates have leveled off confounds earlier studies that attributed it to such things as a more mature, less-violent drug trade or police tactics that focus on high-crime areas.

James Lynch, professor at American University’s Department of Justice, Law and Society, said the reason that crime was down so broadly was difficult to pinpoint.

Two recent possibilities, he said, are a prison population at a record 2.1 million and the terrorism fight’s deterrent effect on more routine street crime.

“Some of the mobilization for terrorism issues may have put a damper on crime,” Lynch said. “It has a chilling effect on a whole lot of stuff.”

The low crime rate also has made the problem much less of an issue in national political campaigns. It is almost never mentioned in campaign speeches by President Bush or Democrat John Kerry, and fewer people than in past years now list crime as a top concern in opinion polls.

The National Crime Victimization Survey is based on annual interviews by Census Bureau personnel with about 150,000 people at least 12 years old.

Other report highlights:

• Violent crime rate has dropped in every income category by at least 40 percent between 1993 and 2003.
• Men were more often crime victims in 2003 than women, except sexual assaults.
• About 29 blacks per 1,000 were crime victims, compared with 21.5 per 1,000 whites and 16 per 1,000 all others.
• Crime victims were more often 24 years old or less.