Steelworkers are about to start making steel again at U.S. Steel’s Granite City Works — and they’re throwing a street party on Saturday to celebrate.

In March, U.S. Steel announced that it was restarting one of its two blast furnaces at the plant and would recall about 500 steelworkers. They were laid off in December 2015 when the company idled its steelmaking facilities in Granite City.

Two years ago, company officials cited challenging market conditions for the shutdown. They now credit President Donald Trump’s decision to put a tariff on imported steel for enabling the Granite City plant to resume steelmaking.

The party is being planned for Saturday because the blast furnace is scheduled to be fired up on Friday, said Dan Simmons, president of United Steelworkers 1899, one of the union locals that represent workers at the plant.

“I hope everybody comes out and joins us and, you know, celebrates what this steel mill means to not only the guys that work here and their families — but what it means to this community,’’ Simmons said.

The party is also a thank you to the community, which helped support steelworkers during the long layoff, he said.

The celebration will begin at 4 p.m. outside the union’s labor temple at State and 20th streets, just a few blocks from the plant.

Follow Mary Delach Leonard on Twitter: @marydleonard