pittsburgh: why did Pittsburgh develop into an early center of U.S. steel production? What are the raw materials and human factors that influence the locations of steelmaking?|||The three basic ingredients in making steel are coal (to make coke), iron ore and limestone. Western PA has local coal and limestone. Iron ore was easy to ship via the Great Lakes and then train to Pittsburgh. Pittsburgh also has a good location and good transportation (Ohio River) and it used to have the labor force to do the job. The most important human factor was Andrew Carnegie. He built Pittsburgh's Carnegie Steel Company, which was later merged with Elbert H. Gary's Federal Steel Company and several smaller companies to create U.S. Steel.