The company was formed in 1892, and was subsequently sold in 1901 in one of the largest business transactions of the early 20th century, to become a major component of U.S. Steel.

[6] Built to show its use of steel in its construction, the building was fifteen stories high and was left uncovered for a full year.

[7] Carnegie Steel made major technological innovations in the 1880s, especially the installation of the open hearth furnace system at Homestead in 1886.

It now became possible to make steel suitable for structural beams and, with the advanced work of George Lauder in arms and armament, for armor plate for the US Navy and the militaries of other governments, which paid far higher prices for the premium product.

Carnegie installed vastly improved systems of material-handling, like overhead cranes, hoists, charging machines, and buggies.

The more skilled union members reacted with the unsuccessful 1892 Homestead Strike along with demands for reduced working hours and against pay cuts.