DETROIT (AP) — Great Lakes Works, the century-plus old blast furnaces that made the steel that built America, is mostly idle now, but the mill — despite social media rumors — has a little life left in it yet.

But steel making in metro Detroit — and America — probably won’t ever be what it was.

The blast furnaces on Zug Island were so powerful that when they were firing, neighbors miles away claimed it caused vibrations they could hear in their ears and feel in their chests, according to the Detroit Free Press.

A year ago, U.S. Steel said it would indefinitely idle major operations at the factories, sending notices to 1,545 employees.

Now, there are about 500 workers left, down from more than three times that a year ago — and just a small slice of what it was at its peak. In the late 1940s, more than 16,000 men reportedly worked there.

The Pittsburgh-based company confirmed recently that primary steel making ended in April. The hot strip mill was shut down in June, but a few operations are ongoing — as long as demand will support them.

“We do continue to run a variety of finishing operations there, at the plant,” company spokeswoman Meghan Cox said. “But our primary steel making, which entails the blast furnaces and iron production, has ceased.”

The company said the mill would operate “with adjustments as needed, in response to market conditions.” It declined to speculate, however, on the future market conditions for steel.

Steel companies, like U.S. Steel, are likely taking a wait-and-see approach as President-elect Joe Biden forms his own steel trade policies and more pandemic vaccinations potentially lift manufacturing restrictions and precautions for their customers.

As a commodity, global demand for steel has climbed steadily in the past few decades. China is the world’s largest producer. In 2018, President Donald Trump slapped 25% tariffs on foreign steel, initially driving up prices.

But it didn’t stop steel mills from making job cuts.

Detroiters have long had a love-hate relationship with the behemoth.

Since the turn of the last century, the blast furnaces provided the steel the nation needed to build automobiles and skyscrapers. At the same time, it took the lives and health of men working in dangerous conditions and polluted the environment.

Operations at the mill had been temporarily halted in the past, most notably in 2008 as a result of the economic downturn, but restarted a year later. This time, though, the fires were permanently put out.

U.S. Steel, which owns Great Lakes Works, did not offer its plans for what it would eventually do with the blast furnaces. At one time, they were reportedly the largest in the world.

In recent years, reports have speculated what would happen to the plant, while employees both lamented the gradual shutdown, and recalled how harsh the working conditions were.

Social media posts, recently — and erroneously — suggested the mill was being closed later this month. One Facebook poster later said he regretted spreading misinformation, which was was “completely wrong.”

In 2016, U.S. Steel — without admitting wrongdoing — agreed to pay a $2.2 million fine and spend an additional $1.9 million on facility upgrades and other environmental projects to settle alleged Clean Air Act violations.

The steel company also agreed to replace a cracked, pollution-emitting bell top on a blast furnace used for making molten iron at its Great Lakes Works facility on Zug Island.

People who lived near the mill complained for years the mill caused what they dubbed “the hum.” The phenomenon reportedly ceased last year when the blast furnaces were shut down for good.

The first blast furnace on the island was built in 1902 by Detroit Iron Works.

It was purchased by a Cleveland company in 1904. A second furnace was added in 1909. The plant became part of the Great Lakes Steel in 1931. A third blast furnace was added in 1938, and U.S. Steel bought the mill in 2003.

Cox said that there’s a lot of “historical lore” about the mill, but U.S. Steel didn’t end up with the records to verify it. “It is sad,” she added, because she’s certainly heard “a lot of cool” stories about the old plant.