Steel has been part of the soul of Pueblo almost since the city’s incorporation 150 years ago. From the 1880s through much of the 20th century, Pueblo was home to Colorado Fuel and Iron, at one point the state’s largest private employer.

The Pueblo steel mill got its start making rails to build the Denver and Rio Grande Western Railroad. Over the years, it turned out all kinds of steel products, and the company that owned it opened mines throughout southeastern Colorado.

CF&I was central to one of the most infamous episodes in state history: the Ludlow Massacre. In April of 1914, Colorado National Guardsmen and militiamen hired by the company fired into a camp of striking mineworkers north of Trinidad. Tents were set ablaze and by the time the ash settled, nearly two dozen people were dead, including 11 children and two women who had hidden from the flames in a crude basement under an infirmary tent.

The massacre helped usher in an era of unionization and stronger labor laws, and eventually led company owner John D. Rockefeller Jr. to give employees a greater voice in their conditions. But it did little to slow CF&I’s growth. And by the post-World War 2 era, the company employed some 12,000 workers in Pueblo itself.

“At that time the United States was experiencing a huge boom in construction projects, building of highways and skyscrapers and other types of infrastructure that required steel,” said Pueblo’s Steelworks Museum curator Victoria Miller.

But the boom days didn’t last, and for much of the past 80 years, the mill’s story has been one of decline.