CHICAGO — A year after this city, the nation's third largest, drew national notice for its staggering number of homicides, killings have slowed here.

Officials in the administration of Mayor Rahm Emanuel, who has faced scrutiny over his handling of the violence, said the improvement was a result of an array of efforts, from new police tactics to after-school and summer programs.

In 2012, Chicago witnessed more than 500 killings, many of them shootings tied to gang rivalries in some of the toughest, struggling neighborhoods. As of Dec. 30, Chicago had reported 413 homicides, a 17 percent drop from the same period a year before and the fewest murders to date since 1965, city officials said.

Shootings were also down by about 24 percent in 2013 from a year earlier, and reports of crimes overall had dropped by about 16 percent. Still, Chicago's death toll remained higher than those in the nation's more populous cities — New York and Los Angeles, both of which reported a decrease in killings as the end of 2013 approached.

"We're pleased, we're not satisfied," Garry F. McCarthy, the superintendent of the Chicago police, said in an interview. "It's progress, not victory. We've put systems in place that are going to keep producing better results moving forward."

As in lots of big American cities, the level of killings in Chicago was far worse a few decades ago; in the 1990s, the yearly death toll here sometimes reached more than 900. But the 506 deaths of 2012 marked an uptick and was a painful reminder of this city's divisions of race and wealth; many of those deaths took place in only about half of the city's police districts, south and west of the prosperous downtown.

By last January, the miserable price of the bloodshed here drew widespread note when a high-school girl who had just attended festivities honoring President Obama's inauguration in Washington was slain as she spent an afternoon with friends in a park not far from the president's home on Chicago's South Side. The girl, Hadiya Pendleton, 15, had no ties to gangs, the authorities said, but had been mistakenly swept into a gang-related retaliation shooting. Michelle Obama attended the girl's funeral here, and President Obama spoke of her during his State of the Union address.

Mr. McCarthy, who was appointed by Mr. Emanuel to run the police department in 2011, made changes aimed at tackling the complications of Chicago's hundreds of increasingly splintered gang factions. He sent more officers — some working overtime, at least initially — into a small number of areas deemed the most volatile. The police created an "audit" of the city's tens of thousands of gang members, aimed at tracking rivalries and where retaliatory shootings might be likeliest.

Critics have questioned whether Chicago, a city facing significant budget pressure thanks to a looming increase in required contributions to workers' pension funds, can ultimately afford to continue to tamp down the violence. The city had spent $96 million this year on overtime for the police by the end of November, city officials said.

But Mr. McCarthy dismissed concerns about the price. "It really worked," he said. "So instead of people saying, 'What are we going to do about the overtime?' they should be saying, 'That was a really great investment in saving lives.' "

About $75 million is budgeted for overtime in 2014, the city said.

"We continue to make significant progress in reducing crime rates to historic levels, and gains are being made in all communities across Chicago," Mayor Emanuel said in a written statement issued by his spokesman. "While this is good news for our children and families, we are not resting. Through strategic policing, smart prevention, sound parenting and stiffer penalties, we will continue working until everyone enjoys the same sense of safety."

And while the year-end homicide statistics marked an improvement citywide, not every neighborhood felt safer — or even noticeably different, residents here said. In September, 13 people, including a 3-year-old boy, were wounded during a shooting involving an assault-style rifle near a pickup basketball game at a South Side park. A gang dispute, the authorities have said, led to the attack.