Primary sourceArtifact1872–1875

Edgar Thomson Steel Works

Carnegie, McCandless & Co. · 1872–1875

Carnegie's first steel mill, built 1872–1875 at Braddock, Pennsylvania, named after his railroad patron and still operating.

Carnegie's first steel mill, the foundation of the industrial empire that financed his later philanthropy.

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Black-and-white aerial view from a wooded bluff looking down on the Edgar Thomson steel works along the Monongahela River. Long industrial buildings with covered loading structures and rail tracks run across the middle; trees fill the foreground and a hazy sky fills the top. — Edgar Thomson Steel Works, Braddock, Pennsylvania, built 1872–1875. U.S. Steel.

About this source

What it is

The Edgar Thomson Steel Works, built by Carnegie, McCandless & Co. between 1872 and 1875 near Braddock, Pennsylvania, was Andrew Carnegie's first steel mill using the Bessemer process. It is now part of U.S. Steel and remains in operation.

Why it matters

Carnegie named the mill after J. Edgar Thomson, president of the Pennsylvania Railroad and an important patron and customer for his steel. The mill marked Carnegie's shift from ironworking and bridge-building into large-scale steel production, the foundation of the industrial empire that later funded his philanthropy.

Look closer

Why would Carnegie name his mill after a railroad executive rather than himself?
What does the long list of engineers, managers, and companies involved tell you about how industrial projects like this were built?
What does an aerial photograph like this show, and what does it hide about the working conditions inside?

This artifact is part of the curated material that grounds the AI version of Andrew Carnegie on Humy.ai — when students ask about related events, the AI can quote it and cite it.