Coney Island’s fun zone, which jumps into high gear Memorial Day weekend, marks a victory of civic order over urban chaos — a milestone as precious to the city as was the rebirth of “Slime Square.”

The boardwalk and environs miraculously morphed from a creepy, 1980s grotesquerie-by-the sea into today’s easygoing pleasure zone that’s a blast for everyone.

Like most of the Big Apple’s recent renaissance hot spots, this one owes itself to our most significant stroke of fortune since the early 1990s: the spectacular drop in crime — especially street crime.

Not a single murder occurred in Coney Island in all of 2018, according to the NYPD. By comparison, the 60th Precinct — which includes Coney Island, Brighton Beach and Sea Gate — saw 21 homicides in 1990.

The death toll didn’t tell the full story. While most victims weren’t Cyclone-riding thrill-seekers, but rather innocent residents of nearby housing projects, the lawlessness spilled into the amusement zone, including on the beach and boardwalk.

Coney Island went into a tailspin in 1966 when developer Fred Trump demolished the Steeplechase Park amusement complex. Although Donald Trump’s father mercifully didn’t get to build the “Las Vegas-style” luxury apartments he wanted at the site, the years that followed came up snake eyes for the city. Middle- and working-class fun-seekers, appalled by Coney Island’s condition, got their kicks in the suburbs — leaving the rides and side shows to rot even further.

In the crime-scourged 1980s, the boardwalk and beach swarmed with predatory youths, drunks and crack dealers. Shuttered rides and restaurants lent a dystopian air. Winter defined a surreal land-and-seascape dominated by the derelict Parachute Jump and ruins of the crumbling Thunderbolt roller coaster.

Only a handful of old attractions kept Coney Island kicking. Just enough brave souls came for the Cyclone, Deno’s Wonder Wheel, restaurants Gargiulo’s and Totonno’s, and hot-dog mecca Nathan’s Famous to keep the whole place from sliding into the sea.

Then, Mayor Rudy Giuliani unleashed the cops as he did in Times Square. I knew times were changing around 1998 when I watched them persuade a scary, tattooed boardwalk hustler to coax his even scarier, mile-long snake back into a basket.

The gradual return of public order restored a tantalizing glimmer of Coney Island’s lost glory. Mayors beginning with Ed Koch entertained various schemes for wholesale redevelopment but were thwarted by fears over Coney Island’s future. The transformation instead occurred one step at a time as law-abiding visitors gradually reclaimed the place and stimulated private and government investment.

Giuliani brought the Brooklyn Cyclones to a new minor-league ballpark. His successor, Michael Bloomberg, lured Italian amusement park builder Zamperla Group to create a new Luna Park with roller coasters even more daring than the Cyclone.

The city restored the crumbling, now-landmarked boardwalk and burnished and illuminated the long-inactive Parachute Jump — a glowing icon for miles around. The New York Aquarium was repaired and enlarged after being nearly wiped out by Superstorm Sandy.

Another abandoned landmark, the 1926-vintage Childs Restaurant, was reborn as a modern eatery; the Ford Amphitheater live-entertainment venue opened next door. The former Shore Theater on Surf Avenue, dark for over 30 years, is now being converted into a boutique hotel.

Today’s Coney Island might be the Big Apple’s most democratic gathering place, teeming with fun-seekers young and old, affluent and poor, of every race and color. Of course, even with all its festive sights and sounds, Coney Island won’t ever again be the early 20th century resort built around three huge amusement parks — Luna Park, Dreamland and Steeplechase — that were unique to their time. Their interwoven stories are related in a compelling new book by Stephen M. Silverman, “The Amusement Park: 900 Years of Thrills and Spills, and the Dreamers and Schemers Who Built Them” (Black Dog & Leventhal Publishers).

But to this Brooklyn-born, lifelong New Yorker whose parents literally forbade me to go there, today’s Coney Island is better than ever — a cheerful mix of attractions that are separately owned by private companies, nonprofit institutions and the city itself. It’s wholesome enough for families, yet with enough honky-tonk to evoke its century-ago predecessor.

The best way to reach Coney Island is to take the el lines to Stillwell Avenue. The once-frightening terminal was redesigned in the early 2000s to resemble a grand European rail station. A first sight of the rides and the ocean from the train brings a thrill you can’t get from any other MTA conveyance.

Silverman writes, “Modern economic realities may have dulled the historic spirit of Coney Island, but the fact that an amusement zone exists at all is something of a miracle.” That miracle was built on the pillar of civic responsibility. In a city with New York’s regenerative powers, it takes only safe streets and public spaces to make all things possible.