Andrew Carnegie was a Scottish immigrant who worked as a factory worker,  messenger boy, and telegraph operator as a child. During the Civil War he helped mage Union railroad lines. After the war he started the Keystone Bridge Company.  The Keystone Bridge Company built bridges out of iron instead of wood. He used the corporate form of enterprise to raise additional capital and bought out competing local companies in the 1870s.

Became rich by investing in oil refineries in Ohio during the Civil War. He formed the Standard Oil Company in 1870. He made deals with railroad companies to give him secret rebates for shipping his oil while they charge higher prices to his competitors. He then started building pipelines to transport his oil. In 1882 he formed the Standard Oil Trust which was the first great industrial trust. I brought 90% of all oil refining in the United States under his control.

J.P Morgan was the son of a banker. His early career was spent reorganizing failing railroad companies. In 1892, he helped Thomas Edison form the Edison Electric Company. After a dispute, Morgan pushed Edison out of the company which he then renamed to the General Electric. In 1895, he formed the J.P Morgan & Company, a commercial and investment banking institution. In 1901, he bought Andrew Carnegie's steelworks and joined them with other steel companies to form U.S. Steel which was the first billion-dollar company in the U.S.

Henry Flagler was John D. Rockefeller's partner in the creation of Standard Oil Company. Rockefeller gave full credit to Flagler for the formation of the company. Later on he helped develop Florida by building hotels. His enterprise also included railroads, real estate, and shipping. He was a main contributor to the growth of Miami and was given the unofficial title" Father of Miami".

Worked in the public interest to prevent big businesses from having too much power. "Every common carrier subject to the provisions of this act shall according to their respective powers, afford all reasonable, proper, and equal facilities for the interchange of traffic between their respective lines, and for the receiving, forwarding, and delivering of passengers and property to and from their several lines and those connection therewith, and shall not discriminate in their rates and charges between such connecting lines."

Worked in the public interest to prevent big businesses from having too much power. "Every contract, combination in the form of trust or other- wise, or conspiracy, in restraint of trade or commerce among the several States, or with foreign nations, is hereby declared to be illegal."