Metropolisation
Metropolisation refers to the process that concentrates populations, activities, and command functions in so-called “mother cities” (the term metropolis originates from the Greek meter polis). Metropolises are interconnected not only with their locality but also with their region, country, and, in some cases, with the global urban network.
Urbanisation is increasing globally, and metropolises play a critical role as driving centres of globalisation, structuring territories at multiple scales. However, the phenomenon is uneven, and metropolises vary significantly in form and function depending on regional and national contexts.
This study is structured into three parts. The first part explores the global urbanisation process. The second part describes the functioning and dominance of metropolises within a global urban hierarchy. The third part analyses the challenges and issues arising from metropolisation and the strategies employed by governments to address them.
#1. A more urban world
#A. The urbanisation process
In 2019, 55% of the global population lived in urban areas. This figure is expected to rise to 65% by 2050.
Urban growth is closely linked to development, as measured by the Human Development Index (HDI), with urban transition being a critical stage. The most developed countries have an urbanisation rate close to 80%, whereas Least Developed Countries (LDCs) have urban populations of around 30%.
It is the less developed countries currently experiencing the most rapid urban transition—similar to the urbanisation process seen in European cities during the 19th century. India, an emerging economy with strong annual growth and a BRICS member, is witnessing significant rural-urban migration (and rural depopulation). While much of India's population remains rural, the pull of cities like Mumbai continues to grow.
#B. The stages of urban transition
Countries are at different stages of urban transition, often linked to the timing of industrialisation. For example, Belgium industrialised early, and today its urbanisation rate is close to 100%.
In contrast, some LDCs, such as Burundi and Niger, have urbanisation rates between 10% and 15% due to the delayed onset of industrialisation. Emerging economies and resource-producing countries represent unique cases, as they may still have significant rural populations while experiencing strong urbanisation and metropolitan growth. China (with its coastal cities) and India (Mumbai), as well as Brazil (São Paulo) and Nigeria (Lagos), exemplify this pattern.
#C. The growth of megacities
#a) In contrast to small and medium-sized cities
The largest cities, known as megacities (those with populations exceeding 10 million), are growing more rapidly than smaller urban centres. This growth results from the concentration of economic activities, which in turn attract large populations. This expansion often occurs at the expense of smaller towns and rural areas, which see populations and resources diverted. In 1975, there were only five megacities, but by 2030 there are expected to be around 40, most of which will be located in the Global South, where urban growth is fastest.
Some regions, such as the United States' Boswash corridor (Boston to Washington), Japan’s Tokaido corridor (Tokyo to Fukuoka), and the Pearl River Delta in southern China (Hong Kong, Shenzhen, Guangzhou), form vast urban regions where cities merge into continuous urban landscapes: megalopolises.
#b) The challenges of growth
Megacities face numerous challenges, particularly regarding housing, infrastructure, and basic services. Housing provision becomes especially critical in megacities with over 30 million inhabitants, such as Chongqing in China, where the government implemented an extensive social housing policy.
In addition, maintaining efficient transport systems is essential to ensure that workers can commute to employment centres. For instance, Shenzhen and Jakarta have expanded their metro systems in response to rapid urban growth.
Basic services, including waste collection, water treatment, and electricity provision, also become more complicated in megacities. In some cities, while water is treated to be potable, the outdated pipe systems used to transport it may result in contamination with heavy metals, making the water unsafe for consumption.
#2. The dominance of metropolises, "mother cities", a crucial hierarchy in globalisation
#A. Mother cities, centralised functions
What constitutes a metropolis? Population size does not define a metropolis (for example, it should not be confused with a megacity, which has over 10 million inhabitants). A metropolis is defined by its connections and influence at local, regional, national, and even global levels.
The term metropolis comes from the Greek meter polis, meaning “mother city,” referring to cities that act as central hubs of population, economic activity, and political command. Metropolisation is the process through which these cities grow in prominence, forming networks of interconnected centres at various scales (national, regional, and global), facilitating the flow of people, goods, and capital.
#B. Financial and business centres
Metropolises centralise critical economic activities, such as finance and international business. Trans-national corporations (TNCs) seek to establish their headquarters in these cities. Some metropolises have Gross Urban Products (GUPs) that exceed the GDP of certain countries; for example, Tokyo's GUP is equivalent to Italy’s GDP, and São Paulo's is higher than that of the Netherlands.
The most powerful metropolises are home to major stock exchanges and are hubs of financial activity. These activities are clustered in Central Business Districts (CBDs), with some metropolises, such as London, Amsterdam, and Hong Kong, having multiple CBDs.
Additionally, the most influential metropolises are frequently located on coastlines or are otherwise well connected to global trade routes, reinforcing their core role in global goods exchanges. By contrast, regions outside metropolises represent the periphery of globalisation.
#C. Influence at various scales
Metropolises exert influence at different scales, from global cities, which concentrate flows of capital, data, people, and goods, to regional metropolises with more limited, but still significant, roles in globalisation. Examples of global cities include London, New York, Tokyo, Paris, and Singapore.
Regional metropolises like Hanoi, Manila, Abidjan, and Lima may not play as prominent a role globally but still exert considerable influence within their respective continents. Smaller metropolises, such as Manaus in Brazil, primarily influence their immediate surrounding region.
#D. Categorising global cities
The classification of global cities varies across research groups, countries, and academic institutions. Sociologist Saskia Sassen was the first to introduce the concept of the global city in the 1990s. Since then, various rankings have emerged, differing based on criteria such as economic activity, research and development, cultural interaction, liveability, environmental sustainability, and accessibility.
Let's take the 2021 Global Power City Index report as a reference and count the criteria that contribute to the influence of metropolises. The criteria are economic activity, research and development, cultural interaction, liveability, environment, and accessibility. By summing up these criteria, we understand that the main challenge for metropolises is connectivity.
Economic activity includes: market size and attractiveness, economic vitality, human capital, business environment, ease, and absence of barriers to conducting business.
Research and development includes: the academic resources available to researchers, the research environment, and an overall innovation criterion.
Cultural interaction encompasses: the potential to create global trends, tourism facilities and accessibility, the density and access to culture, and links with other countries and cities.
Liveability refers to: the work environment, cost of living, safety, and population well-being.
Environment takes into account: sustainability, air quality and comfort, and urban planning.
Accessibility refers to: connectivity to the urban network by air, railways, and roads, the density of the transport network within the city, and the overall comfort of these transports.
The notion of a "world megalopolitan archipelago" (as coined by geographer Olivier Dollfus) suggests that metropolises function as interconnected islands in a global system, with each metropolis striving to dominate the network as a hub of global flows.
#3. Continuous development, problems and new challenges
#A. Connectivity, technology and governance
Governments and public authorities work continuously to enhance the connectivity of metropolises. Improved connectivity facilitates the flow of globalisation’s key actors, such as TNCs, capital, data, foreign direct investment (FDI), human capital, and tourism, into and out of these cities.
The rise of smart cities is transforming urban governance and planning through the use of technology. Smart cities use digital tools, data analytics, and IoT (Internet of Things) technologies to enhance urban services, from traffic management and energy consumption to public safety and healthcare. Cities like Barcelona, Seoul, and Singapore are leading the way, with smart infrastructure that optimises resource use and improves the quality of life for residents. However, the implementation of smart city technologies also raises issues such as data privacy, cybersecurity, and the digital divide, where certain populations may not have access to these technological benefits. As cities continue to innovate, ensuring that smart technologies are inclusive and protect citizens’ rights will be critical.
Effective governance is critical for managing the complex dynamics of large metropolises. Decentralisation, which involves distributing governance responsibilities to local or city-level authorities, can make urban management more efficient. Cities like London, New York, and Tokyo have significant autonomy, allowing them to respond swiftly to urban challenges, whether they relate to transport, housing, or environmental issues. However, in many developing countries, national governments retain strong control over cities, limiting their ability to address localised problems effectively. Successful decentralisation requires robust institutions, transparency, and accountability to ensure that local governance structures can manage urban growth equitably and sustainably.
#B. Urban sprawl and its management
Metropolises often grow vertically, as seen in the development of CBDs with tall skyscrapers in cities like Dubai, Hong Kong, or Shenzhen. However, they also grow horizontally, expanding into suburban areas, edge cities, and rural spaces.
In rapidly developing cities, such as Shanghai (which saw massive expansion following the establishment of the Pudong Special Economic Zone in 1990), urban sprawl has reached extreme proportions. This phenomenon can be exacerbated by real estate speculation, which pushes less affluent populations to the urban periphery, creating challenges for commuter transport systems.
Chinese coastal metropolises have rapidly expanded their public transport networks to accommodate large commuting populations, while cities in the Triad (North America, Western Europe, and East Asia) have experienced slower and more controlled transport expansion.
To combat urban sprawl, cities need to promote higher-density development, invest in efficient public transport systems, and encourage the creation of mixed-use neighbourhoods that reduce the need for long-distance commuting.
#C. Pollution and environmental sustainability
Pollution is another critical challenge facing metropolises, particularly in emerging countries undergoing rapid industrialisation. Double-digit growth in industrial activity has led to severe air, water, and environmental degradation in cities like Shijiazhuang in China, Jakarta in Indonesia, Dhaka in Bangladesh, and Karachi in Pakistan. Air pollution peaks in these cities pose serious public health risks, especially for vulnerable groups such as children and the elderly.
As cities expand, they often struggle with pollution, particularly in rapidly industrialising countries. Air and water pollution are significant issues in many cities, with the burning of fossil fuels, industrial waste, and inadequate sanitation systems contributing to environmental degradation. Cities such as Beijing, New Delhi, and Jakarta have experienced severe air pollution crises, which pose serious public health risks, particularly for vulnerable populations like children and the elderly. To tackle pollution, cities are implementing stricter environmental regulations, investing in clean energy technologies, and promoting public awareness of environmental health issues. Cleaner transport options, such as electric vehicles and improved public transport, are also being prioritised.
With rapid urbanisation comes increased pressure on natural resources and ecosystems. Cities are key contributors to climate change, and many are taking steps to reduce their carbon footprint and mitigate environmental degradation. Initiatives such as the development of green infrastructure (e.g., parks, green roofs, and rain gardens), investments in renewable energy, and sustainable transport networks are becoming priorities. Cities like Copenhagen, Vancouver, and Singapore are models of integrating green spaces and sustainable urban planning to reduce emissions and improve quality of life. Additionally, cities face resilience challenges as they become more vulnerable to climate risks like flooding, heatwaves, and rising sea levels. Urban resilience strategies, including flood defenses and disaster preparedness, are increasingly important in urban governance.
#D. Socio-spatial segregation, migration and urban diversity
Metropolises are also marked by socio-spatial segregation, even in the most cosmopolitan cities. This segregation can manifest through unequal distribution of foreign communities (diasporas) in certain neighbourhoods, as seen in London, Paris, Barcelona, and San Francisco.
There is often a stark socio-spatial divide between slums, CBDs, and high-end residential areas, particularly in cities of the Global South, such as Manila and Mumbai (Dharavi). Gated communities exacerbate this division; they are private residential enclaves surrounded by walls or fences and equipped with security. Gentrification also plays a role. It is the process by which wealthier individuals move into and renovate previously lower-income urban areas. This drives up property values and displaces the original residents.
As wealthier residents concentrate in city centres, poorer populations are pushed to the periphery, reinforcing residential segregation and economic inequality. This division restricts access to essential services such as education, healthcare, and employment for marginalised communities. To combat this, cities must adopt inclusive policies promoting affordable housing, equitable access to services, and balanced urban development.
Migration, both internal and international, plays a major role in shaping the demographic and cultural landscapes of cities. Cities like London, New York, and Dubai are global hubs where diverse populations live and work. Migrants, often filling labour gaps in urban economies, also bring cultural richness that contributes to the vibrancy of city life. However, migration can also lead to social tensions, particularly when cities struggle to provide adequate housing, education, and healthcare services for newcomers. Integrating migrants into urban societies, while ensuring social cohesion and reducing xenophobia, is a growing challenge that cities must address to remain inclusive and dynamic.
#E. Metropolises in competition
Metropolises are constantly in competition with one another to increase their global standing, attract investment, and enhance their influence. Public authorities strive to develop their cities to improve their attractiveness, aiming to climb higher in the urban hierarchy to dominate other metropolises. The underlying principles driving this competition are those of economic liberalism, shaped by globalisation. Cities seek to enhance their connectivity, infrastructure, and liveability, thereby attracting global firms, capital, talent, and tourists. Ultimately, this competition contributes to the growing global influence of some metropolises, while others struggle to keep pace.
In the context of globalisation, metropolises increasingly compete to attract international investment, talent, and tourism. Cities like Tokyo, London, and New York are not only financial hubs but also cultural centres that influence global trends in art, fashion, and technology. To remain competitive, cities must continuously innovate and enhance their global connectivity, quality of life, and economic opportunities. This competition can, however, exacerbate inequality between cities, with wealthy global cities growing richer while smaller or less connected cities struggle to keep pace.