Natrona Steel Works, Pennsylvania

Allegheny Ludlum, also known as ATI, produces around 600,000 tons of steel per year from this plant at Natrona, on the Allegheny River, with a blast furnace. Nearby is the Brackenridge Works, a larger facility, but with no blast furnace. Allegheny Ludlum is a specialty metals company based in Pittsburgh, which makes titanium, zirconium, and many other materials for defense and industry. It has owned Teledyne since 1996, and has more than a dozen metals plants.