What industry did John D Rockefeller make his fortune in?

Answer 1

By the end of the Civil War, Cleveland was one of the five main refining centers in the U.S. (besides Pittsburgh, Philadelphia, New York, and the region in northwestern Pennsylvania where most of the oil originated). In January 1870, Rockefeller formed Standard Oil of Ohio, which rapidly became the most profitable refiner in Cleveland. When it was found that at least part of Standard Oil's cost advantage came from secret rebates from the railroads bringing oil into Cleveland, the competing refiners insisted on getting similar rebates, and the railroads quickly complied. By then, however, Standard Oil had grown to become one of the largest shippers of oil and kerosene in the country. That is the answer.