New York City Mayor-elect Zohran Mamdani’s smile carried him a long way toward being elected. And he used his affability again on Friday, turning the meeting he had requested with President Donald Trump into an Oval Office lovefest.

Now it’s time for the mayor-elect to employ the power of smiling to make day-to-day life better for New Yorkers when they are compelled to interact with city employees. Mamdani needs to call on the 300,000 city employees to show warmth, respect and courtesy to the public. The spirit of a smile.

Walk into a city agency or court building seeking help, and you’re likely to get barked at and herded like a dumb animal. Ask a Metropolitan Transportation Authority employee why the train isn’t coming, and you’re apt to hear, “Can’t you read the sign?” followed by a muttered “dumb f–k.” It’s a bruising experience.

I went to family court at 111 Centre Street last Thursday to be appointed as a guardian for a 95-year-old woman bed-bound in a nursing home. Arriving at the appointed time of 9:30 a.m., I found 80 people, in a line snaking around the outside of the building, waiting to enter and go through the one available metal scanner.

I inched ahead in the line until I was third from the entrance. A burly man in a guard uniform suddenly came through the door, held his arm horizontally in front of me, and yelled an order for all of us to turn around and proceed to the entrance at the back of the building. Everyone who had made it to the front of the line would now be at the back of the line. I calmly said “no,” and that I had waited once and would like to enter, and I started to walk around him to the door. He held his arm out to stop me and barked his order again, adding, “Do you think you’re someone special?”

“Yes,” I replied, adding below my breath, “We are human beings.” I pushed my way around him and into the building, taking the two women behind me in as well.

The fact is, everyone in that line deserved dignified treatment — but that’s not the treatment being meted out by employees at 111 Centre Street.

When I got upstairs, I took a seat outside Judge Ilana Marcus’ courtroom. Noon arrived, and I still hadn’t been called. I pulled open the courtroom door a crack to see if the elderly patient’s case was still being discussed.

At that point, a court guard pushed through the door, screamed at me for opening the door, and refused to answer any questions about whether I was even in the right hallway. When I tried to speak, she shut me down.

That’s how people too often are treated in city agencies and courtrooms. And it’s reflected in the low ratings New Yorkers give city services. Only 27% rate them overall good or excellent, reports the Citizens Budget Commission, though New Yorkers give high ratings to fire protection and garbage collection.