Urban systems in medium-sized cities: the two forces and the emergence of a flower structure

This article discovers the unique dynamics shaping medium-sized cities (populations between 100,000 and 500,000) and addresses a less explored area: understanding how the balance between centralization and population density creates distinct urban forms. Medium-sized cities often exhibit a predominantly monocentric structure, with central hub concentrating economic activities, government services or cultural institutions. But as they expand, population density begins to shape more localized clusters of amenities in outlying areas, forming what we term a “flower structure.” In this setup, a central hub is surrounded by “petals” or clusters that each offer services close to home while staying connected to the city centre. This research positions medium-sized cities between the polycentricity often observed in larger urban centres and the monocentric patterns typical of smaller towns. Using Košice, Slovakia, as a case study, we employ regression models to trace how distance from the core and population density work together to shape these service clusters. The findings reveal a blend of centralized and decentralized spaces that offer practical accessibility in different parts of the city. This model encourages urban planners to think beyond a single core, opening up new strategies for the 15-minute city concept, which emphasizes self-sufficient neighbourhoods. The study also suggests a need for “interstitial development” to connect these clusters, creating a more cohesive, resilient city that supports the diverse needs of its residents. • The “flower structure” describes urban clustering in medium-sized cities. • Centralization and population density drive service distribution patterns. • Regression models in Košice, Slovakia, reveal urban clustering tendencies. • Local service clusters align with the 15-minute city for accessible planning. • Centralized and decentralized models offer insights for urban planners.