J.R. Simplot became a billionaire by selling what food item to McDonalds?

J.R. Simplot became a billionaire through frozen French fries supplied to McDonald’s.

John Richard “J.R.” Simplot built his fortune in Idaho’s potato industry. His company developed commercially practical methods for producing frozen French fries, solving a major problem for fast-food restaurants that needed consistent quality and year-round supply.

In 1967, Simplot reached a handshake agreement with McDonald’s founder Ray Kroc to supply the chain with frozen fries. The arrangement helped McDonald’s standardize one of its most important menu items as the restaurant expanded rapidly. Simplot’s business later became one of the world’s major producers of potatoes, frozen foods and agricultural products.

The answer refers specifically to French fries, but the fries were not sold as individual servings directly by Simplot to customers. His company supplied frozen fries to restaurants, which cooked and served them. Simplot’s wealth also grew through fertilizer, phosphate mining, cattle and other agricultural ventures, so the McDonald’s relationship was a crucial part of his fortune rather than his only business.