Question

Between 1870-1900 a decline in the cost of this necessity helped create a rapid expansion of global trade and growing economies?

Answer 1

Energy.
The Second Industrial Revolution, also known as the Technological Revolution,was a phase of rapid industrialization in the final third of the 19th century and the beginning of the 20th. The First Industrial Revolution, which ended in the early-mid 1800s, was punctuated by a slowdown in macroinventions before the Second Industrial Revolution in 1870.