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How does a conurbation form when neighboring cities expand?

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Dense crowd of people walking through the brightly lit Shibuya shopping district in Tokyo, Japan, surrounded by colorful store signs and billboards in Japanese and English. — city Crowds of people in Tokyo's Shibuya shopping district.

A conurbation forms through the territorial coalescence of two or more sizable cities when their peripheral zones expand and grow together. This process is driven by the outward sprawl of urban settlement, where the quantitative increase in development leads to a qualitative transformation of the landscape.1

As neighboring cities expand, their once-distinct boundaries blur, resulting in a continuous network of urban communities. This phenomenon is often fueled by economic growth and population expansion, which encourage construction at the "urban fringe". Over time, these polycentric urban zones become complexly interlocked both socially and physically.213

While this growth can create vast, interconnected regions, it often relies on extensive infrastructure development, such as roads and utilities, to support the dispersed nature of the resulting urban environment. Notable examples of such large-scale urban concentrations, sometimes referred to as megalopolises, can be found in the United States, Great Britain, Japan, and the Low Countries.3415