The entrepreneurs of the Gilded Age profoundly changed the way Americans did business. Some such as John D. Rockefeller managed to buy out his opponents and to intimidate railroads into giving him discounts to haul his product all over the country at reduced rates. By buying out opponents, he could make the oil industry more efficient by using his money to better streamline the refining business. Andrew Carnegie controlled the iron and coal mines needed to make steel--he also controlled the smelting industry and the industries which made and sold steel girders and railroad supplies to builders. These two men employed millions of people, albeit at low wages and in dangerous conditions. They also created much of the materials needed to make modern cities. If I had to pick one captain of industry who changed America the most, I'd have to go with Carnegie. Without him, modern skyscrapers and railroads would be more expensive. His suspension bridges were in use for over one hundred years. His work in the coal industry, while controversial in terms of environmental damage and worker hardships, developed the Allegheny region of the United States and brought jobs to the area. Also, Carnegie gave money to libraries and symphony halls which still bear his name today.