The nation's crime rate was unchanged last year, holding at the lowest levels since the government began surveying crime victims in 1973, the Justice Department (search) reported Sunday.

Since 1993, violent crime, as measured by victim surveys, has fallen by 57 percent and property crime by 50 percent. That has included a 9 percent drop in violent crime from 2001-2002 to 2003-2004.

The 2004 violent crime rate — assault, sexual assault and armed robbery — was 21.4 victims for every 1,000 people age 12 and older. That amounts to about one violent crime victim for every 47 U.S. residents.

By comparison, there were 22.6 violent crime victims per 1,000 people in 2003. The Bureau of Justice Statistics (search) said the difference between the rates in 2003 and 2004 was statistically insignificant.

Murder is not counted because the bureau's study is based on statements by crime victims. In a separate report based on preliminary police data, the FBI found a 3.6 percent drop between 2003 and 2004 — from 16,500 to 15,910. Chicago was largely responsible for the decrease.

The survey put the rate for property crimes of burglary, theft and motor vehicle theft in 2004 at 161 for every 1,000 people, compared with 163 the year before.

Many explanations have been advanced for decline in violent crime, including the record prison population of more than 2 million people, the addition of 100,000 police officers since the mid-1990s and even a deterrent effect that terrorism might have had on street crime.

"Success has 1,000 fathers," said Mark A.R. Kleiman, an expert on crime control policy who teaches at UCLA.

Kleiman said the victim survey probably does not take sufficient account of a growing problem with gang violence that has been widely reported across the country. The leveling off of the crime rate also should be viewed as disappointing, he said.

"My sense is that complacency is not justified. This rate means we're down to about twice the level of crime when I was growing up in the 1950s," he said.

The Justice Policy Institute (search), which advocates alternatives to incarceration, said the report offered good news and further reason to "begin investing in community-based policing and local organizations that succeed in increasing public safety."

The National Crime Victimization Survey (search) is based on annual interviews by Census Bureau personnel with about 150,000 people at least 12 years old. The FBI does a separate crime study based on reports it receives from thousands of law enforcement agencies nationwide.

Other highlights of the Justice Department report:

— Blacks, men (except in cases of sexual assaults) and young people were victimized most often.

— Nearly two-thirds of women knew their attackers, while men were just as likely to be attacked by strangers.

— In 2004, just under one-quarter of all violent crimes were committed by an offender armed with a gun, knife or other weapon.

— The rates of rapes and robberies have dropped by nearly two-thirds since 1993.

— The West had the highest property crime rate in 2004 (204 crimes per 1,000 households), while renters were victims more often than homeowners (201 crimes versus 143 crimes per 1,000). City-dwellers were far more likely to be victims of property crimes (215 crimes per 1,000) than suburban or rural residents (143 and 134 per 1,000, respectively).