"Increased employment, more education, community-based policing and changing demographics are certainly reasons," said Daniel Glaser, a University of Southern California sociologist and past president of the American Society of Criminology.
Denver, Detroit and Nashville saw a sudden rise in slayings, but FBI statistics show serious crime has been decreasing nationwide. Homicides plummeted to a 20-year low in Los Angeles and a 30-year low in New York.
Homicides in Los Angeles sank 20 percent this year to the lowest level since 1977. There were 566 homicides in the city as of Dec. 14, 143 fewer than for all of 1996. The city hasn't had fewer than 600 homicides since 1977, when 574 people were killed.
"It seems that society has gotten tired of so many murders. People may finally be weary of all the violence," Deputy Police Chief Martin Pomeroy said Monday.
As of Sunday, New York City's death toll stood at 756, down from 961 a year ago and the lowest level since 1967. New York's homicide total peaked in 1992 with 2,262 killings.
Other cities reported murder rates that have dropped by more than half from 1991. In Dallas, 209 homicides were reported, compared with 217 for all of 1996 and 500 in 1991. In Houston, there were 231 killings, down from 261 last year and a 57.1 percent drop from 1991.
Other cities with lower numbers than last year were Chicago (749 from 787); Newark (56 from 94); Minneapolis (57 from 86); Baltimore (307 from 329); New Orleans (262 from 350); Memphis (156 from 180); and San Francisco, (65 and 84).
San Francisco police Lt. David Robinson echoed the sentiments of many experts when he attributed the drop partly to community-based policing.
"We're not just arresting people, we're keeping the peace. It's the difference between a police officer and a peace officer," Robinson said.
Detroit was one of the cities that bucked the trend. The nation's 10th-largest city reversed a five-year decline in homicides this year with the death toll rising to 454 after 428 murders in 1996.
"One year could be a blip and not enough to predict a trend," said Larry Dubin, a law professor at University of Detroit-Mercy.
Nashville already has a record 112 homicides, compared with 89 in 1996. Homicides were also up in Denver, with 76 murders through Sunday compared with 68 through Dec. 28 last year.