Mega urban agglomeration in the transformation era: Evolving theories, research typologies and governance

The contemporary landscape of urban agglomeration studies has been experiencing a constant shift in research themes, which calls for a comprehensive and systematic revisit to urban agglomeration studies. This study conducts a systematic review of urban agglomeration studies, develops a general typology of urban agglomeration, and delineates its evolving theories. It also probes into the two major sub-concepts of urban agglomeration research, arguing that there are sub-themes in these two similar concepts that investigate economic activities in urban agglomerations with distinctive foci. With a bibliometric analysis and intensive review of selected articles, we analyze the development of theories in different terrains of urban agglomeration research and their underpinning influencing factors and dynamics. These help depict the overlaps and differences of the sub-concepts and different terrains. Finally, a systematic architecture is established for trans-disciplinary urban agglomeration research that integrates the fragmented multi-disciplinary studies involved and serves as a benchmark to position subsequent studies in urban agglomeration research.