Chicago's large, diverse automotive industry specialized in truck, bus, and taxicab assembly, as well as automotive-parts manufacture, in the first decades of the twentieth century. From having just a handful of companies before World War I, by the mid 1920s Chicago grew to include more than 600 firms that were producing a wide assortment of automotiverelated products. This large, successful industry emerged out of two sets of advantages: First, Chicago's well-developed production factors—ranging from relatively advanced transportation and industrial facilities to a large labor force and an effective entrepreneurial business class—promoted industrial growth. Second, the automotive industry's production practices, elaborate division of labor, and intense set of interfirm relations encouraged metropolitan expansion. Even though the city's firms functioned both regionally and nationally, they were also deeply embedded within a local world of innovation, interaction, networks, financing, and servicing. Further adding to these advantages was Chicago's distinctive geography, which enabled a dense complex of linked, interrelated firms to flourish and contributed to the automotive industry's success before 1930.