How did John D. Rockefeller and Andrew Carnegie increase the size of businesses?

John D. Rockefeller and Andrew Carnegie significantly expanded their businesses through strategic practices and innovations in their respective industries. Rockefeller, through the Standard Oil Company, utilized vertical integration to control all aspects of oil production and distribution, effectively reducing costs and increasing efficiency. Carnegie, in the steel industry, employed the Bessemer process to streamline production and also embraced vertical integration by acquiring iron ore mines and railroads. Both men capitalized on economies of scale and strategic partnerships to dominate their markets and grow their enterprises.