Chisun Yoo Successfully Defends Dissertation on Rethinking Megaregions: A Network Approach

The College of Design congratulates Chisun Yoo for the successful defense of their dissertation, "Rethinking Megaregions: A Network Approach" on Tuesday, April 18th, 2023.


Rethinking Megaregions: A Network Approach

The emergence of a new scale, the megaregion, is one of the prominent issues in regional planning. Megaregions are concentrations of population, employment, and infrastructure and reflect the economic geography of countries, producing a majority of economic output. Accordingly, analyzing, delineating, and planning for megaregions are imperative in developing governance and policies, thereby assuring megaregions promote sustainability and economic competitiveness. Federal institutions and multiple state governments in the US address megaregions as an important planning unit. However, there are remaining challenges of megaregion planning.

One of the significant challenges is delineating megaregions. Without boundaries to which plans or policies apply, it is difficult to articulate a way forward to implement megaregion planning. Thus, well-defined boundaries are a desirable precondition for spatial planning at any scale. Nevertheless, the delineations of megaregions to date have several shortcomings, requiring new approaches. Megaregions have barely been studied from the network perspective. The borderless flow of capital has connected local areas and regions to the global network, making connectivity of places critical in regional dynamics. The delineations to date do not adequately reflect the recent changing trends, such as freight activities and changing human mobility patterns. Further, there are overlooked factors that contribute to forming megaregions. The cultural connection is often overlooked in delineating megaregions, although it is suggested as an important factor in the literature since it can function as an amalgamation of regions and enhance the functionality of a region as a whole. Business networks have also been overlooked, and they can integrate different areas into one functional region.

This research delineates megaregions in the US using the network analysis approach, conceptualizing megaregions as a multi-layered network of freight flow, human flow (commute & non-commute), cultural connections, and business networks. Megaregions are identified from the four networks, and their intra-dynamics and network structure are analyzed. The first analysis constructs and analyzes the freight flow network between counties. Publicly available freight data is first disaggregated to the county level using a machine learning algorithm. Then the county-level freight flow network is constructed and analyzed. The second analysis includes both commute and non-commute trip patterns to identify the human flow network. By using the private-sourced mobility pattern data, movement patterns related to points of interest are aggregated at the county-level, to construct the human flow network. These first two analyses examine the economic relationship that binds places into a megaregion. The third analysis explores shared cultural identity among places by analyzing cultural heritages and their cultural attributes. The distribution and attributes of cultural heritages data are acquired, then a two-mode network consisting of two types of nodes – cultural identity and counties (location of heritages) is constructed to identify regions connected by the traces of cultural heritage. The fourth analysis captures the network that exists at the intersection of economic relationships and cultural connections by analyzing chain and franchise business (CFB). Using the private-sourced business data, a two-mode network consisting of CFBs and their counties (business locations) is constructed. In the final stage of the study, the four networks are merged and analyzed with community detection to find functional regions at the megaregion scale. Ultimately, a new map of US megaregions is delivered as a final outcome.

This study contributes to the literature and guides policymakers at different scales by identifying and delivering a comprehensive figure of megaregions in the US. While the growing importance of megaregions has yielded official recognition of megaregions by federal government agencies, the map of megaregions is outdated and chiefly centered around freight activities. By analyzing a set of different connections and spatial interactions, this study provides the most comprehensive map of megaregions in the US. Furthermore, as the author explores several facets of megaregion forming, contributes to several fields, including regional planning, transportation planning, regional economic development, regional governance, and cultural geography.


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