Ten days, three Manhattan deaths. Tessa Majors, Erica Tishman and Katherine Miller — all killed on Gotham’s increasingly ungoverned streets in the waning days of 2019. Each loss is the sadder because each was preventable. New York is at risk of backsliding in its 30-year effort to use data to keep its citizenry safe. Random “accidents” and crimes aren’t all that random. They are failures of local government.

Tessa Majors was the 18-year-old Barnard freshwoman murdered in Morningside Park in the early evening of Dec. 11. Early indications, although hardly assured, are that three teenagers stabbed her to death in an ­attempted mugging.

Majors’ death shouldn’t have happened. It was the culmination of a pattern that should have been disrupted. For 2019, up ­until the eve of her murder, Morningside Park had experienced 20 robberies, nearly triple the number of the previous year.

Whether the perpetrators of the previous robberies committed the homicide is irrelevant. Criminals felt emboldened in the park this year, and robbery turned to murder. Police, whose support among the political class has waned as the public has felt safer in recent decades, didn’t do enough to disrupt this feeling.

What about death from above? Erica Tishman, 60, a prominent architect, died last Tuesday after being clonked in the head by crumbling pieces of a building façade at Seventh Avenue and 49th Street. Like Majors, Tishman could have done little to prevent her own death: She didn’t have the data.

But the city could have done something. Eight months ago, the Department of Buildings cited the structure from which the debris fell for a critical violation: failing to maintain the façade. Yet Buildings inspectors never followed up. The city had the data in hand to avert this loss but didn’t use it properly.

It is a bitter piece of New York irony: Seemingly every sidewalk in Midtown is covered with ugly scaffolding, just not the sidewalk under the building that is actually falling down.

Then, last Thursday, Miller, a 26-year-old, was crossing Broadway in Soho in the crosswalk when the driver of a large truck backed up suddenly, running her over and killing her.

Impossible to predict? No: As Streetsblog points out, the truck had amassed 723 violations in 18 months. Many of these violations were for misconduct such as double parking in Midtown, which obstructs pedestrian views, and blocking bike lanes.

What kind of city, with its poor management of the streets, tolerates truck drivers who systemically engage in dangerous behavior as the cost of doing business? Brad Lander, a Brooklyn City Council member, has long been pushing a bill to ­impound vehicles involved in multiple moving violations. But he has failed to garner the votes necessary to pass this uncontroversial measure.

A murder, an accident and a traffic crash. All may seem unrelated. But they are all part of New York’s tenuous hold on public safety. Pedestrian deaths are up slightly for the year, to 114 people killed, including four people killed in just 16 hours late last week.

The murder rate, muddled by the NYPD’s strange habit of “reclassifying” dozens of murders whose precipitating violent incident took place years before, is roughly flat. But the city’s insistence that overall crime remains at record lows sounds increasingly more plaintive than boastful, as if this is the best we can do. Traffic safety advocates, to their credit, are never satisfied with near-record lows.

In fact, safe-streets advocates and crime victim advocates don’t often pay attention to one ­another, but they should. 1990 was the peak year for both traffic violence, with 701 walkers, cyclists and car drivers and passengers killed, and murder victims, at 2,262. Last year, the figures were 203 and 295 people, respectively.

A street where a would-be mugger can carry a gun or knife around fearlessly is the same lawless environment where a car or truck driver can run a red light fearlessly: Nobody with the power to stop them cares.

New York, by the numbers, is statistically safe. But it wasn’t statistically safe for Majors, Tishman and Miller, and it hasn’t felt safe for people walking around this holiday season not knowing whether to look behind a tree for a knife-wielder, at the street for speeding drivers or at the sky for crumbling buildings.

Gotham has failed to use one of its biggest stores of wealth — data — to save as many lives as it can. In 2020, the city must ­resolve to save more of the people ­behind the numbers.

Nicole Gelinas is a contributing editor of City Journal. Twitter: @NicoleGelinas