Franklin E. Zimring, a law professor and criminologist at the University of California, Berkeley, said the city may find it hard to reduce violent crime much further. “At some point, rates of life-threatening violence in the City of New York are going to scrape bottom,” he said. “Any police official that says we’re going to try to push it down another 50 next year has been smoking substances that until rather recently were illegal.”

As of Dec. 30, there were 287 homicides in New York, down five from last year. That drop continued a steady decline since 1990, when there were 2,262 murders. Robberies in 2018 were also down by nearly 8 percent from the previous year, and shooting incidents decreased by 4 percent. The number of people shot fell to 894, from 933.

Yet, 1,760 rapes were reported as of Dec. 23, compared to 1,438 at the same time last year. The police said the final year-end totals for reported rape and hate crimes would not be released until later this week.

Experts on sex crimes said the increase in reported rapes does not mean more people were assaulted. Some welcomed the rise as a sign that more rape victims were going to the authorities and undergoing the ordeal of having evidence collected.

“We view it as good news because it means that more people are feeling confident to come forward and report the rape,” said Sonia Ossorio, the president of the National Organization for Women of New York. She added: “The clear indication is that more people are reporting their assaults rather than suffering in silence as so many people have done for so long.”