In the context of Donald Trump’s globe-girdling career, his repair job 30 years ago on an old ice skating rink might seem to merit a mere footnote. But Trump’s reopening of Central Park’s Wollman Rink in 1986 was a defining moment for him — and for many New Yorkers, a hell of a first impression.

The Wollman Rink, opened in 1949, was a beloved Manhattan postcard icon. It appeared in countless movies, including “Love Story.” But it was falling apart, and then-Mayor Ed Koch closed it in 1980.

The city promised to reopen it by 1985. But Koch’s incompetent commissioners and contractors let the job run $12 million over its original $4.7 million budget, and by 1986, the finish line was nowhere in sight.

Enter Trump. The young Trump Tower developer was known more for self-promotion and for an ugly, name-calling feud with Koch over tax abatements and zoning rules.

In June 1986, Trump brashly offered to reopen the rink before Christmas. “If Koch doesn’t like this offer,” Trump said, “then let him have the same people who have built it for the last six years do it for the next six years.”

Koch held his nose and gave Trump the keys. Trump got the ice rink reopened to the public on Nov. 1. Maybe any able construction company could have done the same. But Trump’s success was a tonic to a crime-torn, crumbling city that needed some good news. It showed how private enterprise could handily whip government bureaucracy.

Wollman was a tiny project. But, unlike disputes over taxes and zoning, it told a story everyone could understand. It made Trump a hero, at least for a time. And more than any of his skyscrapers, it lent him the “can-do” reputation that propelled him into the White House.