Travel in the usa for M. Flagler, and S.V. Harkness, Rockefeller was soon operating Standard Oil, the largest oil refinery in Cleveland, Ohio. Rockefeller’s foresight and keen business sense soon led the company to expand by purchasing other refineries, and they were soon producing over 12 million barrels a year. By 1875, Standard Oil had spread its operations across the country. A trust agreement was signed in 1879 and amended in 1882 giving the power of this huge corporation to nine men who oversaw the operations of 40 companies and who received a portion of profits. Travel in the usa 2016.