"Economists and geographers have distinguished between three historical configurations of North American industry: concentrated in the late 19th and 20th centuries, decentralized in the mid-20th century, and distributed at the end of the 20th century. Each of these eras constructed distinct spatial organizations and shaped urban form in particular ways. The shifts between these modes of production are evident as ruptures in the urban form that preceded them, leaving previous spatial modes obsolete and abandoned in their wake."