CHICAGO — A year after this city drew new attention for soaring gun violence and gang bloodshed, creating a political test for Mayor Rahm Emanuel in President Obama’s hometown, Chicago has witnessed a drop in shootings and crime. Killings this year have dipped to a level not seen since the early 1960s.

So far in 2013, Chicago homicides, which outnumbered slayings in the larger cities of New York and Los Angeles last year, are down 34 percent from the same period in 2012. As of Sunday night, 146 people had been killed in Chicago, the nation’s third-largest city — 76 fewer than in the same stretch in 2012 and 16 fewer than in 2011, a year that was among the lowest for homicides during the same period in 50 years.

In recent months, as many as 400 officers a day, working overtime, have been dispatched to just 20 small zones deemed the city’s most dangerous. The police say they are tamping down retaliatory shootings between gang factions by using a comprehensive analysis of the city’s tens of thousands of suspected gang members, the turf they claim and their rivalries. The police are also focusing on more than 400 people they have identified as having associations that make them the most likely to be involved in a murder, as a victim or an offender.

As Mr. Emanuel, who has said he intends to run for re-election, begins the second half of his first term, it is unclear whether the months of lessened violence will generate a lasting trend, particularly given a spring of rainy, chilly weather here that some experts say may have kept people off the streets and contributed to the relative calm.