Polypropylene bags are strong puncture resistant bags used for transporting a wide variety of materials. United Bag’s Synthetic Industries division, created in the 1960’s, became one of the first companies to extrude and weave polypropylene. This division began its career by manufacturing sandbags to protect American Soldiers at war. American’s also used the sandbags for flood protection, erosion control, and more. United Bags later sold Propylene Bags for commodity dry goods, as well as the USDA for exporting grains from America to other countries in need of nutrition.