For the last hundred years, Michigan's auto industry has been a force in America, still accounting for a fifth of all American manufacturing. Although there once were hundreds of automobile manufacturers in the United States, by 1913 almost 80 percent of all cars were made in the Detroit region. Few places in the world are so closely associated with a single industry. New technologies and practices developed there also transferred to non-automotive goods design, manufacturing, and management, including advances in computer modeling, materials, mass production, and vertical integration. The local economy has diversified over time, but the region remains the hub of transportation manufacturing, with research and design centers, testing facilities, parts producers, corporate headquarters, and a workforce of 90,000. Chrysler, Ford, and General Motors remain rooted there, and more than 120 automotive manufacturers and suppliers are headquartered in Oakland County alone. After the 85 billion dollar automotive bailout in 2009, optimism reigns in a region that knows manufacturing is back.