The U.S. poultry industry is the fastest growing sector within the meat complex. Concentration and efficiency of U.S. poultry production have grown steadily since the mid-1930s. Poultry is the most vertically integrated of the meat industries and vertical coordination, the linking together of successive stages of production and marketing through ownership or contracting, has spread rapidly, allowing poultry producers to maintain lower per-unit production costs and higher profits relative to those in other meat industries. Virtually all commercial poultry is grown under contract or by integrated firms. Due to the vertical integration, production decisions, from the hatchery supply flock through final production, are made by vertically coordinated management. This allows for the analysis of poultry production as part of a single production process, unlike beef and pork production.