Students and staff unveil murals dedicated to Bradbury Heights Elementary School teacher NeShante Davis and her 2-year-old daughter, Chloe Davis-Green. They were among the Washington region’s 2016 homicide victims. (Lynh Bui/The Washington Post)

The District ended 2016 with 135 homicides, down 17 percent from the previous year, but the annual total for the Washington region held steady because the number of killings rose in several suburbs.

Prince William County, in Northern Virginia, marked its deadliest year on record. It had 22 killings — more than double the 10 recorded in 2015.

The 97 homicides investigated by Prince George’s County police in 2016 marks the second year in a row that the Maryland jurisdiction saw its homicide count rise, with an increase of 20 over the previous year.

Counting a handful of ­cases that emerged Friday and Saturday in the District and Prince George’s, there were at least 301 homicides last year in Washington and its surrounding cities and counties, compared with 305 the year before.

The upward trend in many local jurisdictions echoes the pattern in big cities nationwide, according to surveys and analyses from law enforcement experts. The numbers, however, are generally not as alarming as the surge in 2015 that prompted police chiefs from major cities to gather in the District for a summit on the violence.

Mary Rich, mother of slain DNC staffer Seth Rich, appeared at a news conference in the District’s Bloomingdale neighborhood in August. The 2016 homicide remains unsolved. (Michael Robinson Chavez/The Washington Post)

“They’re up again [in 2016], but maybe not quite as bad as the year before,” said Darrel Stephens, ­executive director of the Major Cities Chiefs Association.

As of Sept. 30, 37 of 65 agencies the association surveyed reported an increase in homicides compared with 2015. But only five or six major cities are responsible for driving up homicide figures nationally, Stephens said. Most notable is Chicago, where the city’s 700-plus slayings are more than double the combined total in the Washington region.

The District was among the major U.S. cities where killings spiked in 2015, leaving frightened residents to cite crime as one of their top concerns for the first time in many years. But in 2016, the District was in the minority of large cities that saw a reversal: Its homicide total fell to 135, from 162 in 2015.

Montgomery County had half as many homicides in 2016 as the 30 it recorded in 2015. That was a significant turnaround for the Maryland jurisdiction after one of its deadliest years in two decades.

The homicide tally in Fairfax County rose to 18, up from 12 in 2015, and it edged upward in a few other Northern Virginia communities.

Criminologists with the Brennan Center for Justice say while many major cities are again seeing a rise in killings, it’s too soon to call it a national crime wave. They also add that overall crime is level, holding at historic lows.

D.C. police say crime is down in most categories. Burglaries are down 16 percent, and robberies and incidents of stolen vehicles are down 12 percent. Overall crime in Prince George’s County is down about 9.5 percent.

Interim D.C. police chief Peter Newsham said repeat offenders, robberies and the prevalence of firearms fueled the 2015 spike. In 2016, police targeted robberies and repeat offenders to drive down homicide numbers.

While killings were down this past year in the District, many attracted widespread attention.

Christmas weekend in the city contained a violent burst with five homicide victims in four days, including Tricia McCauley, a 46-year-old yoga instructor and actress who was killed on her way to a holiday dinner.

Earlier in the year, at least three teens were killed at a bus stop or Metro station.

And the District recorded the death of Deeniqua Dodds, 22, who police say was killed during a robbery by a man targeting transgender women.

Seth Rich, a 27-year-old staffer with the Democratic National Committee, was fatally shot during what D.C. police describe as an attempted robbery in July. That case, which remains unsolved, quickly set off conspiracy theories, including one suggesting that he handed emails to WikiLeaks that embarrassed the DNC during a contentious presidential election. WikiLeaks fueled the rumor without confirming it by offering a $20,000 reward in the case.

Many of the Northern Virginia killings involved family members, including an Arlington teenager accused of stabbing his father to death and an Alexandria woman charged with killing her husband during a fight over their dog. In Fairfax, Roy Eugene Rumsey, 58, killed his 2-year-old daughter and then himself before setting their home on fire, according to police.

Some Virginia cases remain mysteries.

Retired World Bank economist Johan De Leede was shot and killed at his home in quiet and upscale Mason Neck, baffling those who knew the 83-year-old civic activist. George Mason University student Hosung Lee, 21, was beaten and stabbed by a mob at a party on April 24; friends drove him home and put him in bed, according to court documents, where he was found dead the next day.

The record number of slayings in Prince William has unsettled the Virginia jurisdiction about 30 miles from the District. Law enforcement officials point to gang activity and domestic violence as some of the reasons for the historic high.

“It certainly gets my attention, there’s no doubt about that,” Prince William Chief Barry Barnard said. The rise in homicides “just reinforces with me we need to work harder and do what we can in terms of prevention, education, information, treatment and enforcement.”

Officer Ashley Guindon, 28, one of the Prince William homicide victims, was shot and killed on her first day on the street as she was answering a domestic violence call.

Two weeks later, Prince George’s County Officer Jacai ­Colson, 28, was killed in what authorities have described as an “attack” on a police station by three brothers seeking notoriety by posting a recording of the shooting online. Colson, an undercover narcotics detective, responded to the chaotic scene in street clothes when he was shot by a fellow officer who mistook him for an assailant, prosecutors said.

It was a difficult year for first responders, who also mourned the death of Prince George’s County firefighter John “Skillet” Ulmschneider, 37. Ulmschneider and another firefighter were breaking down the door of a home where they believed a man was suffering a medical emergency. As they entered, the homeowner inside fired, thinking the firefighters were intruders. Ulmschneider was killed. The homeowner was not charged with murder but ­faces a trial in 2017 on illegal handgun charges.

In addition to the 97 homicides investigated by Prince George’s police, Greenbelt police investigated the killing of a man shot in his condo and the FBI investigated a fatal stabbing at the Suitland Metro station.

Most of the homicides in Prince George’s from 2016 stem from domestic violence, drug cases or disputes between people who knew each other, Police Chief Hank Stawinski III said.

In May, Eulalio Tordil killed his estranged wife outside a Prince George’s high school before continuing on a shooting rampage in Montgomery County that killed two others and wounded three more.

Domestic violence is “something that we take very seriously, but unfortunately in many cases, the first thing we know about it is the call for shots fired or someone who has been stabbed or killed,” Stawinski said.

Prince George’s State’s Attorney Angela D. Alsobrooks said one of the worst cases in 2016 was the Feb. 2 killings of NeShante Davis, 26, and her 2-year-old daughter, Chloe Davis-Green. Prosecutors say the girl’s father shot the child while she was strapped in her car seat and killed her mother over child-support payments.

“The babies in particular are hard to accept,” Alsobrooks said. “It was a tough year for us.”

Nine months after the mother and daughter were killed, students gathered outside Bradbury Heights Elementary School, where Davis had taught. On the day Chloe would have turned 3, the school unveiled a mural in honor of the mother and daughter. Beneath brightly colored pictures featuring a wounded heart with wings, a chorus of students sang Michael Jackson’s “Man in the Mirror.”

“If you wanna make the world a better place,” they sang, “take a look at yourself, and then make a change.”

Dana Hedgpeth, Justin Wm. Moyer, Victoria St. Martin, Peter Hermann, Rachel Weiner, Dan Morse and Justin Jouvenal contributed to this report.