The four primary urban models that have been developed to explain the layout and spatial structure of cities are:
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Concentric Zone Model: Developed by Ernest Burgess in the 1920s, this model suggests that cities grow outward from a central point (the CBD - Central Business District) in a series of concentric rings. Each ring represents different land uses, such as residential areas, commercial zones, and industrial sectors.
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Sector Model: Proposed by Homer Hoyt in 1939, the sector model argues that cities develop in a series of sectors or wedges radiating out from the CBD, influenced by transportation routes. Different socio-economic groups settle in specific sectors based on their preferences and proximity to resources.
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Multiple Nuclei Model: Introduced by Chauncy Harris and Edward Ullman in 1945, this model posits that cities do not grow around a single center but have multiple centers or "nuclei" that serve as focal points for different business and social activities. These nuclei can develop due to various factors such as transportation hubs or ethnic communities.
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Urban Realms Model: This model highlights the decentralized nature of modern metropolitan areas, particularly in the context of post-World War II suburbanization. Proposed by James E. Vance Jr., it suggests that cities can be segmented into individual realms that operate independently, with their own commercial centers and residential areas, often linked by transportation networks.
These models serve as frameworks for understanding the complex patterns of urban development and land use in cities.