The pressure tank made possible the development of the Chicago meat industry in the United States, with its concentration in one geographic area, because it allowed the economic disposal of byproducts which would otherwise overwhelm the environment in that area. At first, small companies that sprang up near the packers did the rendering. Later the packers entered the rendering industry. Gustavus Swift, Nelson Morris, and Lucius Darling were among the early pioneers of the U.S. rendering industry with their personal backing and/or direct participation in the rendering industry.