Chapter 19 went over the "Century of Important People," where in addition to that it also went over some crucial events that led to Amrican prosperity into the 19th and 20th century. One of the main factors that contibuted to this rise in economic growth was an increase in a growing middle, but was also due to new innovations, inventors, and industrial entrepreneurs that became to go on the rise as well.
As these events took steam so did the railroad industry that allowed for transportation of goods, services, and people to be spread across the nation. Among the top entrepreneurs in this was a man named J.P. Morgan who establishes a huge trust in in the railroad system in addition to steel, which ends up bringing about a mass amount of centralization and power to many.
Another entrepreneur was Rockeffeller who made his living off the oil refining business. He also created new types of innovation like new management styles such as the "horizontal business" that basically monopolized everything in in oil refining. In contrast to this process another growing business person know as Carnegie controlled every part of the steel business through his mangament system know as "vertical integration". It was this system that allowed him to control everything from top to bottom of his business.
With these new innovations came more production and efficiency. Profits were increased and costs were low. All of these things led to America becoming what it is today but socially it would cause a large rift between the rich and poor as new innovations have the ability to create tensions among many people but especially employers and employees.