What were the most revolutionary social and economic developments of the last quarter of the nineteenth century?

What was the Industrial Revolution, and how did it impact the organization of society, the production of goods, and transportation? 
September 13, 2019
What strategies did Charles II and James II employ to try to gain more centralized control over England’s American colonies? What did James hope to accomplish by creating the Dominion of New England?
September 13, 2019

What were the most revolutionary social and economic developments of the last quarter of the nineteenth century?

Question Description

What were the most revolutionary social and economic developments of the last quarter of the nineteenth century? How did different groups of Americans respond to those changes and how effective were their responses? What role did government play.