Why might the first steel factories have been built in Pennsylvania?

For the history of earlier processes, see History of ferrous metallurgy. For recent history, see History of the steel industry (1970-present).

The history of the modern steel industry began in the late 1850s; steel has become a staple of the world's industrial economy. This article is intended only to address the business, economic and social dimensions of the industry, since the bulk production of steel began as a result of Henry Bessemer's development of the Bessemer converter, in 1857. Previously, steel was very expensive to produce, and only used in small, expensive items, such as knives, swords and armor.