- J.R. Simplot built an empire as a potato farmer and supplier in Idaho, becoming the largest shipper of potatoes during WWII. In the 1960s, he supplied most of McDonald's French fries. - McDonald's fries became popular in the 1930s-40s when cooked in hot oil. Simplot invested in freezing technology to create frozen fries that tasted like fresh when cooked in oil. - McDonald's fries contain beef flavoring and cottonseed oil, which gives them their unique taste. However, this caused issues for Hindu and vegetarian groups who were unaware of the animal products.