Dean Mazzarella’s day starts at 3 a.m. when he hops out of bed and promptly posts a good morning message on Facebook to his fellow “3 o’clockers.” Despite the early hour, dozens of Leominster residents, some working the third shift, greet him in the comments.

“Good morning Mr. Dean!”

“Mornin’ captain!”

Before he was elected mayor of this sleepy city in North-Central Massachusetts, Mazzarella worked nights as a Leominster police officer. Decades later, he still hasn’t been able to fix his sleep schedule. His days are long, but he doesn’t mind. The constantly-in-motion 68-year-old has plenty of energy to spare for someone who hardly sleeps five hours a night.

“I like to watch the city wake up in the morning,” he said.

Mazzarella uses the early hours to prepare for meetings, plan his schedule, or respond to residents who message him directly about potholes, parades, or taxes. He lives by a rule he calls his “sunset clause,” making sure to call back every person who reaches out to his office before the end of the day.

“People count on us,” he said. “We’re going to work hard like they do, and we’re going to be responsive.”

When he gets to his office, he will host his near-daily “morning briefing” live online, where he chats about anything he sees fit, which is most often politics, gas prices, and things going on around the city. Every Thursday, Mazzarella also hosts his public access TV show “Inside Leominster” during which he can be found doing anything from giving a budget presentation to interviewing Santa Claus.

It’s hardly surprising that after more than three decades in office, Mazzarella seems recognized by virtually everyone he passes by on Main Street as he walks through the city he’s lived in all his life. Perhaps more remarkable for the leader of a city of more than 40,000 residents is that the recognition often seems to cut both ways.

“Dean! What’s happening?” a construction worker shouted at him from across the street on a sunny afternoon in May. Mazzarella shouted his name back and stopped to talk.

There’s no gimmick that is beneath Mazzarella. On any given day, he might hand out a free coffee voucher to a resident that reports a pothole to City Hall or give someone a ride on the Flamingo Express – a free, golf cart-style shuttle service named after the city’s iconic manufacturing symbol that Mazzarella rolled out to help transport people to and from downtown businesses that have been affected by parking changes and street closures around an ongoing brook stabilization project.

In many ways, he is the quintessential mayor seen in movies – accessible to all and everywhere at once. Most people agree that he makes the city of 44,000 feel much more like a small town.

He’s even been compared to George Bailey – the ever-selfless protagonist in Frank Capra’s beloved 1946 film “It’s a Wonderful Life” – who sacrifices his dreams to help his community. Mazzarella doesn’t think of himself like that, although it’s one of his favorite movies, he said. But a longtime friend said the shoe fits.

“George Bailey believed in his community, and Dean believes in his,” said former state senator Bob Antonioni. “His passion is Leominster.”

That passion has fueled him through more than 32 years in office, making Mazzarella the longest-serving mayor in Massachusetts history, quietly surpassing former mayor Michael McGlynn of Medford, who served for 28 years before stepping down in 2015.

Gateway Cities like Leominster are not easy places to lead. These former industrial hubs suffered from the long-term decline in manufacturing following World War II. The hollowing out of those economic anchors and the poverty and blight that have often followed defy quick fixes. But that doesn’t keep impatient voters from voicing frustration at the polls, with Gateway City mayors thrown out of office with some regularity.

Mazzarella’s immediate predecessor, Jack Mahan, served just one term as mayor before the then-first-time candidate sent him packing. Before that, Steve Perla served just two terms. Fitchburg, a neighboring Gateway City, has seen six mayors in the time that Leominster has seen one.

Mazzarella has defied the odds, managing to transform the city, limit his list of enemies, and remain an ever-present, zealous leader on his way to completing 17 two-year terms. One key to that is his ability to be defined by his successes rather than his failures, as Leominster voters have chosen him time and time again, notwithstanding a handful of controversies in City Hall over his years in office.

Despite an electoral touch other officials would die for, Mazzarella comes off far more as affable everyman than calculating politician – a quality that some say is exactly why he has endured politically for so many years.

“I think the art of being successful at politics is not appearing to be a politician,” City Councilor Mark Bodanza said.

Local leaders and residents marvel at his staying power, but “Mayor Mazz” – known for his practical solutions, fiscal conservatism, and relentless energy – suggests the secret to it is not that complicated.

“Government is a lot simpler than people think,” he said, explaining that he runs the city like a business.

It’s a line often invoked by elected officials, but for Mazzarella, the quip is backed by plenty of first-hand experience: He owns not one, but three, local businesses in Leominster. Like any successful business owner who must keep customers satisfied while not giving away the store, he seems to have mastered the tricky balance of keeping Leominster residents happy while also keeping the city fiscally sound.

“People pay a lot of money for government, especially in this state,” he said. “They’re all my customers, no matter who they are. If it’s important to them, it’s important to me.”