Final answer:
Pittsburgh became a major steel center due to its access to essential natural resources like iron ore and coal, its strategic location which allowed for efficient transport and trade, and the vertical integration strategies utilized by industry leaders like Andrew Carnegie.
Step-by-step explanation:
The natural resources that contributed to making Pittsburgh, Pennsylvania, a major steel center included an abundance of iron ore and coal. Iron ore was mined in Minnesota and transported via the Great Lakes to Pittsburgh, providing the essential raw material for steel production.
Equally important was the availability of coal, which was mined in Pennsylvania, West Virginia, and other parts of Appalachia, serving as a critical energy source for the intensive steel manufacturing processes. Pittsburgh's strategic location at the confluence of the Allegheny and Monongahela Rivers to form the Ohio River created unique transport and trade opportunities that were advantageous for the steel industry.
With its industrial advantages, natural resource availability, government support in the form of tariffs, and investment from businessmen like Andrew Carnegie who utilized vertical integration strategies, Pittsburgh became synonymous with steel production and dominated the industry, outpacing even Britain's output by the turn of the century.