President Trump on Tuesday visited a massive new plant in western Pennsylvania that converts the region’s huge natural gas deposits into plastics — saying, “This would have never happened without me.”

Trump spoke at Shell’s nearly completed Petrochemicals Complex in Monaca, which will provide hundreds of jobs to the struggling region near the Ohio border.

But critics claim it also will become the largest air polluter in that part of the Keystone State, an area hit hard by manufacturing job losses and hungry for investment.

Trump said his administration was “restoring the glory of American manufacturing” and making the nation energy independent.

“We don’t need it from the Middle East anymore,” Trump said of oil and “clean, affordable, all-American natural gas,” adding that the plant’s union employees were “the backbone of this country,” sparking chants of “USA! USA!” from the plant’s workers.

Trump also repeated a joke at the expense of environmentalists who criticized the new facility as a dinosaur in an era when ocean pollution caused by discarded plastics was making headlines.

With gas, “when the wind stops blowing, it doesn’t make any difference, unlike big windmills, which destroy everybody’s property values, killing all the birds,” he said.

Earlier, before leaving for Pennsylvania, the president blamed ocean plastic pollution on Asian nations.

During his speech, Trump also touted his margin of victory in Beaver County, the number of times he’d visited the key swing state — 13 — and slammed rivals Joe Biden and Elizabeth Warren.

“What a group. Pocahontas and Sleepy Joe. I don’t think they give a damn about western Pennsylvania,” he said.

He also said he wanted union members to tell their leaders “I hope you’re going to support Trump” in 2020.

“And if they don’t, vote them the hell out of office,” he said.

The company was given massive tax breaks to build the petrochemicals complex, along with a $10 million site development grant, with local politicians eager to accommodate a multibillion-dollar construction project.

It will use a process in which molecules are broken down at high heat, turning fracked ethane gas into a precursor for plastic.

Trump earlier weighed in on a variety of topics as he left New Jersey, where he’s vacationing at his golf club.

On the see-sawing stock market, he said, “We have a lot of artificial numbers from other countries because they’re all devaluing their currencies. They’re really doing things that aren’t very good for their countries, in my opinion. But, short term, it’s very good for their countries. Long term, possibly not.”

On gun background checks, Trump said, “I am convinced that Mitch wants to do something. I’ve spoken to [Senate Majority Leader] Mitch McConnell. He’s a good man. He wants to do something. He wants to do it, I think, very strongly. He wants to do background checks, and I do too, and I think a lot of Republicans do.”

With AP