Studies of cities and urbanization are confronted with significant theoretical and methodological challenges as the urban question is reposed at the city-regional scale. Normative understandings of city-regions as sites of economic innovation and distinct political actors on the world stage belie the complex processes underlying their production. This has significant implications for social justice and political practice. This dissertation engages the challenges of city-regional urbanization through a critical comparative analysis of urban transportation institutions and infrastructure in the Chicago and Toronto city-regions. Focusing on long-term historical and spatial structures, the study demonstrates how multiscalar political, economic and social processes crystallize in specific urban formations and in tum, how processes of urbanization shape urban governance and practices of everyday life. The dissertation develops three central theoretical innovations. First, it introduces a geographical historical-materialist comparative framework to examine the contingent evolution of city-regional formations in space and across time using a cross-national perspective. Second, it reframes urban transportation as a key realm of political economy inquiry, redressing the limitations of traditional transportation geography and the poststructural approaches which dominate urban infrastructures literature. Third, it incorporates diverse urban, suburban and post-suburban spaces within an overarching theorization of city-regional urbanization as an expression of centripetal and centrifugal forces. Qualitative methods are used to uncover and analyze socially-entangled and geographically-disparate urban relations. The empirical analysis reveals that the prioritization of particular scales of mobility spurs the emergence of new city-regional topologies which do not neatly align with territorially-defined forms of state space. Strategies of regionalization are as likely to open new fissures in city-regional space as they are to fuse collective regional agency. The convergences and divergences witnessed between the Chicago and Toronto city-regions illustrate the place-specific path dependent properties of institutional and infrastructure fixes that highlight the importance of historically and geographically sensitive comparative research. The dissertation's dialectical and comparative contributions open the city-region as a multifaceted, multiscalar and multilayered object of analysis. It concludes by outlining how the study's dialectical approach to city-regional urbanization can inform debates on urban transformation and social change
