Historically, this era produced some of America's wealthiest and most powerful industrialists. One of these is John D. Rockefeller, born in Richford, New York, in 1839, who began his working life as an assistant bookkeeper in Cleveland, Ohio. In 1863, Rockefeller invested his savings into an oil refinery and, two years later, he took over the company. By 1870, he had established his own oil refining company, Standard Oil, which grew to control 90% of the country's refineries and pipelines, making him one of the richest and most successful industrialists of his time. (See the first reference link provided).
Another industrialist is Andrew Carnegie who was born in Scotland in 1835 but emigrated with his family to Pittsburgh in 1848. As a young man, Carnegie worked in the telegraph office of the Pennsylvania Railroad but quit after the Civil War because he saw huge potential in the burgeoning steel industry. Through the Keystone Bridge Company, Carnegie made his name by replacing wooden bridges with steel ones. Over his lifetime, Carnegie amassed a personal fortune of $310 billion. (See the second and third reference links provided).