The phrase 'the greatest thing since sliced bread' refers to Otto Frederick Rohwedder's invention of the automatic bread slicing machine in 1928. Before this, bread was sold in whole loaves because it went stale very quickly once sliced. Rohwedder solved this by designing a machine that not only sliced the bread but also immediately wrapped it in moisture-proof paper. This made the sandwich an even more convenient everyday food. The first brand to use the machine was the Chillicothe Baking Company in Missouri, and the product was so popular that bread consumption in the U.S. increased significantly as people began eating more toast and sandwiches.