John D rockefeller was the most influential businessmen of the late 20th century because he founded a Standard Oil Company, and at one time controlled 90 percent of the oil refineries and pipelines in the United States, which led him to become a billionaire. He also bought out his partners, took over the refinery, expanded it and formed the Standard Oil Company. Another accomplishment is he established numerous philanthropic charities, which he gave away more than $500 million. He helped distribute donations to American schools and colleges, find cures for diseases such as meningitis, eradicate hookworm in the southern states, and promote medical research, scientific achievements and the arts. His philanthropic charities were the University