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

John D. Rockefeller and Andrew Carnegie expanded their businesses through different strategies: Rockefeller utilized horizontal integration by merging oil companies to dominate the petroleum industry, while Carnegie employed vertical integration by controlling every aspect of steel production, from raw materials to transportation. Both focused on reducing costs and improving efficiency, allowing them to outcompete rivals. Additionally, they leveraged innovative technologies and strategic partnerships to further strengthen their market positions.