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The Evolution of Technological Knowledge Across Space and Time


Technological change is a powerful force in economic and social life. Technological change is both an endogenous and a disruptive process because inventors create new technologies by recombining existing technological ideas and because new technologies often drive older technologies and their associated capital and skills into obsolescence. Technological disruption resonates in the economies of cities, producing both local economic growth and decline, because city-regions are a scale at which many of the factors of production are coordinated.

In the existing literature, there is broad agreement that knowledge builds on itself endogenously, and there is some recognition that innovation is disruptive with consequences for city-regions. Despite these acknowledgments, the sources of knowledge that inventors used to create historical inventions have not been systematically documented, the question of how new city-regions enter the process of endogenous knowledge production has not been resolved, the geographical distribution of breakthrough innovation has not been described nor explained, and the mechanisms through which inventors amass the technological knowledge needed to innovate in rapidly-evolving knowledge environments have not been adequately studied.

In light of the above research gaps, this dissertation makes four contributions. First, it develops a method called knowledge phylogenetics and uses that method to create a long-run genealogy of technological knowledge containing over 8 million patented inventions created between 1836 and 2014. Second, it uncovers a general process that city-regions go through as they begin to become centers for innovation, involving the importation of non-local and disruptive ideas that are used to initiate local knowledge production. Third, it documents the extent to which breakthrough innovation is concentrated in large and knowledge-diverse cities, how that concentration changed over the 20th century, and how those changes resulted from asymmetric improvements in different types of communication technologies. Fourth, it calculates the productivity benefits that inventors receive from working in teams and from the experiences that they accumulate over time. In this regard, the dissertation shows that inventors do not benefit from the experience that they accumulate over time because inventors struggle to learn quickly enough to keep pace with the advances made in their knowledge fields.

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