1.
Background
The earliest notion of a hierarchy of cities argued that a city's pre-eminence could be the result of one of three conditions: antiquity, walls or privilege [1]. In the 18th century, new ways of comparing cities began to emerge with an emphasis on population and central functionality. The modern-day idea of a hierarchy of cities is ascribed to scholars such as Christaller, Lösch, Perroux, among others and which gave rise to the central place function. The work of these scholars was and is, considered important as it introduced the characteristics of central functions which determine a city's position within the overall hierarchy of an urban system [2,3,4]. The outcome is an urban system comprising lower-order settlements (large in number) and higher-order settlements (few in number), each having different impacts on and contributions towards development conditions [5]. The rationale alluded to the notion that settlements of a higher order tend to offer a larger variety of functions/services and are, consequently, spaced further apart and referred to as multifunctional, thereby having a greater impact on development. Conversely, settlements of a lower order offer a smaller variety of functions/services and are usually closer to one another and referred to as monofunctional, thereby having a lesser impact on development.
In the context of the South African urban system (see section on the South African urban network), a functional index was developed by the Council for Scientific and Industrial Research (CSIR) for the delimitation of the economic catchment areas of each settlement in the country [6]. The index was subsequently used to determine nested patterns of higher- and lower-order centres in the country and was considered an appropriate proposition to classify cities as either primary or secondary. However, although the index provides for a balanced approach, John [4] asserted that due to the growing interest in the subject of metropolitan regions, that which constitutes secondary cities in the South African context is still greatly underdeveloped. The aim of the paper is to furnish a potentially unobstructed approach when identifying secondary cities in South Africa. To achieve this, the outline of the paper will be as follows 1) what is a secondary city? 2) the South African urban network, 3) mixed methods of profiling secondary cities in South Africa, and 4) interconnected regional networks.
2.
What is a secondary city?
Secondary cities can be defined as those cities in the hierarchy of towns and cities of a country that function as cores within territorially organised sub-national regions but being subordinate to the core regions within the national spatial area [7]. Marais and Cloete [8] articulated that although the concept secondary city has become integrated as part of development parlance; there is no clear definition of what a secondary city entails. The concept insinuates that secondary cities are those cities that find themselves below the very apex occupied by primary cities. It is not clear where the notion originated from, however, according to John [4] it would appear that it originated from Friedmann [9] who applied the concepts of primary and secondary cities in a global context, which allowed for the concept to be devolved towards a national context. However, according to John [4], there is no universally accepted definition of that which constitutes a national hierarchy of cities. Many analysts simply refer to a continuum when describing hierarchies. Despite the lack of a concrete definition, it is clear that the general approach or debate focuses on primary and secondary cities as the apex of a hierarchy.
Hierarchies tell us something about urban systems and the role that particular urban areas play in a national or global structure. However, within a country, the criteria for defining a national hierarchy of cities may follow different approaches. For example, the concept primary city was first used by Jefferson [10] to describe cities that emerged as the most populous during a country's urbanisation process i.e. a primate city is disproportionately larger than any other city. Therefore, when considering Jefferson's notion, primate cities were seen as typically much larger than their nearest rival in the urban hierarchy. Although most definitions identify primary cities as the towns with the largest population, countries in the contemporary world would define primary and even secondary cities in different ways [4].
Brand [11] alluded to the notion that settlements or cities are classified into various functional types. According to him, these functions are generally referred to as "central functions" and the characteristics of central functions such as, the number and types of commercial, industrial and service functions, ultimately determine the city's position within the hierarchy of cities, which also determines the city's place of performance and dominance. The outcome is an urban system consisting of lower-order settlements (large in number) and higher-order settlements (few in number), each having different impacts and contributions [5]. Evident from central functions is the notion of a city and hierarchy:
1. A city is generally distinguished by its relative size in comparison to other urban areas, but also by its functions. A variety of indicators, invoking population, and population density, number of dwellings, economic function, and infrastructure are used in classifying cities. In many ways a city is easily identified as a large human settlement that serves as a centre of population, commerce and culture, however, there is a great diversity in and between cities. Cities continue to grow and cover a complex, interlinked functional area often made up of multiple towns [12].
2. A "hierarchy" refers to a system in which members (city) of an organization (country) are ranked according to relative status or authority (dominance). The importance of ranking cities yields the following: firstly, it tells us that within a system of cities, some cities will grow to be larger (population and economy) than other cities; secondly, it refutes the expectation of an optimal size city; and lastly, it establishes cities as belonging to an interrelated network where one city's growth and development affects other cities. The linking of cities not only improves the operational and economic efficiency of a city, region or country, in addition, it creates a myriad of new economic opportunities. More specifically, it creates an integrated network of systems that support the flow of goods, improved infrastructure, increased and more efficient interactions and expanded business involvement, advancing economic integration [11].
If primary cities have the strongest impacts and contributions, why consider secondary cities as fundamental? According to McKinsey [13], the international spotlight turned to secondary cities as the principal drivers of global economic growth. Secondary cities are considered important catalysts for a more balanced and dispersed growth across a country and are seen as important for two basic reasons:
1. Secondary cities are seen as alternative urban centres, to relieve pressure from primary cities since migrants from rural areas normally flock to secondary cities first. This is especially important from a national context where urbanisation skewed economic space development, with most economic and demographic activities occurring in only a few cities. The South African context provides a good example considering that more than 50% of economic activities and more than 40% of population distribution occur in the Gauteng (City of Johannesburg; Tshwane and Ekurhuleni), Cape Town and Durban (eThekwini) regions alone.
2. Secondary cities will play an important catalysing role relating to their surrounding hinterland i.e. secondary cities having central place functions, in other words, secondary cities act as markets for the agricultural produce of their surrounding farmlands, as administrative and service centres for their hinterlands and as interconnected links between cities and functional regions i.e. according to Bolay and Rabinovich [14], secondary cities mediate between rural areas and the larger urban areas.
The key question is; what constitutes a secondary city? Originally Rondineli [15] made the argument that a country normally has only one primary city—the city with the largest population—and that all the other towns or cities with a population count above 100,000 are considered secondary cities. With population size as the main criterion to identify a city's position, much of the academic literature draws on demographer Kingsley Davis' definition of a population size between 100,000 and 500,000 to identify secondary cities, which in essence implies that a country can have more than one primate city. Beyond population size, more recent debates from organisations such as the World Bank (WB) [16,17,18,19], European Union (EU) [20] and major policy think-tanks have begun to look at various other characteristics that could be considered important to define secondary cities. Table 1 illustrates what is considered international characteristics of secondary cities.
3.
The South African urban network
South Africa's cities, towns and localities have developed and became hierarchised over the course of history during which population settlements and their distribution have been influenced by colonisation, segregation, industrialisation and globalisation [21]. From 1911, South Africa has undergone an extended phase of intense urban growth with areas, such as Johannesburg, Cape Town and Durban (eThekwini), agglomerating into dominating economic spaces [6]. The end of Apartheid in 1994 was hailed with optimism by many as South Africa became one of the most advanced countries in Africa, with thriving cities integrated into global economies [22].
The political changes after 1994 had a profound impact on population and economic distribution patterns [23]. The reason is considered against the background of colonialism and Apartheid when areas were (spatially) excluded, and this exclusion hampered economic development and growth. During the period after 1994, when Apartheid had ended, many people who had been prevented from migrating in the past, left rural areas for urban areas. This migration of people—mostly characterised by large numbers of African people and largely triggered by Todaro's [24] "bright lights syndrome" —was essentially productivism-oriented i.e. when people migrate primarily with the aim of finding employment [22,25]. The migration caused unprecedented population explosions in towns and cities of all sizes in the country. National government introduced several acts, policies and programmes aimed at redressing the spatial legacies of colonial and Apartheid rule. The government initiatives were directed at strengthening economic development, creating strategic regional, inter-regional and inter-governmental planning platforms [23,26,27].
There is a growing international awareness that location and place, which in essence refer to regions and urban areas, are important elements for growth and development. The growing international awareness has had an important influence on various development approaches promoted by organisations such as the United Nations (UN), the Organisation for Economic Co-operation and Development (OECD), the European Commission (EC) and the World Bank (WB), where extensive rethinking followed, which promoted the benefits of urbanisation as a result of the advantages cities offer for economic and social development. According to Van Huyssteen et al. [6], the CSIR developed a regional functional index as part of the National Spatial Trends Overview project commissioned by the South African City Network (SACN). Subsequently, the Presidency and the Department of Provincial and Local Government (DPLG) (and later Cooperative Governance and Traditional Affairs [CoGTA]) used the index to inform Cabinet on urban development policy aspects as well as during the process of developing a National Urban Development Framework (NUDF) (and later Integrated Urban Development Framework [IUDF]). The development of the index was based on a classification of settlement patterns considering three main functionalities [26]:
1. Size—Reflects the agglomeration of economies and population.
2. Function—Indicates an area's economic role, e.g. mining, manufacturing and tourism, and its role in terms of public and private service delivery.
3. Institutional legacy—Reflects inherited characteristics of past policies, particularly the land-use policies that fostered economic and residential segregation within cities.
Applying the functional index allowed for the delimitation of the economic catchment areas of each settlement in the country and was used, simultaneously, to determine nested patterns of higher- and lower-order centres in the country's hierarchy of central places. Functional analysis entails the characterisation of regional economic systems, in terms of dominant functions and their order of magnitude in their central places, to the actual and potential systematic linkages and relationships between economic composition and places. The importance of the index is found in the latter showing how the country can be subdivided into functional areas based on the economic catchment areas of higher-order centres, which, in turn, will determine spatial targeting: The functional index provides a mechanism to profile, identify, calculate and analyse a set of development information and trends pertaining to the range of towns and cities across South Africa. This simplifies the analysis of the network of towns and cities and their hierarchical and functional relationships in relation to economic spaces. The index has subsequently been used in the National Development Plan [NDP] as a parameter to classify cities in South Africa [23,28].
The index provides a description of a "network of towns" as a continuous landscape, which is interrelated through complex economic, social, political and environmental forces. This means that the discrete consideration of lower-order centre development as completely distinct from higher-order centre development is, therefore, no longer valid. Instead, the index provides a balanced approach, which addresses both ends of the continuum rather than lower-order centres in isolation from higher-order centres. In summary, the index provides an inclusive development framework that complements the current and emerging economic development in South Africa. Table 2 provides a breakdown of the categories and classification criteria, defining the South African urban system and, ultimately, the distribution of economic spaces.
According to the classification, there are five main urban systems, with City regions being the most dominant. The City regions comprise Gauteng (City of Johannesburg; Tshwane and Ekurhuleni), Cape Town, Durban (eThekwini) and Nelson Mandela Bay (Port Elizabeth)—each having the highest level of economic activities. A spatial analysis of the urban categories suggests that the City regions and cities significantly dominate the South African economic spaces. Furthermore, a sector analysis of the City regions and Cities not only identifies diverse economies that play a significant role as the core cylinder of South Africa's agglomeration economies, but also that City regions and Cities provide key linkages for comparative advantages and development opportunities [6,29].
In retrospect, city regions and cities could potentially be considered an appropriate criterion to classify primary and secondary cities. However, although the above index provides for a balanced approach addressing both ends of the continuum, John [4] asserted that the notion of what constitutes secondary cities in the South African context is hugely underdeveloped. The reason revolves around the growing interest in the subject of metropolitan regions. Currently, eight South African cities i.e. Johannesburg, Pretoria (Tshwane), Ekurhuleni, Cape Town, Durban (eThekwini), Port Elizabeth (Nelson Mandela Bay), East London (Buffalo City) and Bloemfontein (Mangaung) are governed by metropolitan regions and may therefore also be reasonably considered as South Africa's primary cities. However, this declaration has led many South African cities to question what changes or economic dynamism need to occur for a city or town to be considered an aspiring metro. Are secondary cities the same as being an aspiring metro or do the two types of apexes offer different opportunities and contribute different investments to the national space economy? To shed light on this notion, the following sections of the paper will focus on varying approaches employed to profile secondary cities in South Africa as well as a potential unobstructed or differentiated approach that sanctions a degree of objectivity.
4.
Mixed methods of profiling secondary cities in South Africa
Our research methodology is based on a pragmatic paradigm, using a sequential mixed-method methodological approach. Case studies, as part of our research design, together with intervention research design form the core of our empirical analysis. In the view of Marais and Nel [30], research interest in secondary cities has steadily been growing since 2011. The interest as mentioned was triggered by the growing interest in the subject of metropolitan regions. The South African government, urged by political pressure, expanded the number of metropolitan areas from six to eight (see previous paragraph). This prompted the South African Cities Network (SACN) to initiate and fund research on secondary cities, focusing on how government should treat secondary cities differently in policy and programmes. Besides the focus of the SACN, secondary cities have also been receiving increasing policy attention, which includes renewed international attention in the New Urban Agenda [31]. John [4] alluded to the notion that due to the underdeveloped nature of what or how to approach secondary cities, there is no official list of secondary cities available in South Africa. To shed light on the dilemma of an underdeveloped nature we first undertook a comparative analysis examining a set of case studies. We focused on four distinct cases, namely 1) National Treasury (National Department) applying international characteristics as an indicator; 2) CoGTA (National Department) who developed a set of Intermediate City Municipalities (ICMs) applying weightings as an indicator; 3) integrated focusing on spatial change and the mechanisms that influence spatial change; and 4) population grid cells intersected with point data deriving selection criterion at specific population size intervals. Lastly and to promote an alternative that sanctions a greater degree of objectivity, we looked at the role central functions play as an important determining factor when establishing a city's place, by measuring the degree of interaction that exists between cities. For the paper we used the data descriptively.
4.1. National treasury
National Treasury, although considered by Marais and Cloete [8] as arbitrary, provided a quasi-official list, which forms part of Treasury's Cities Support Programme (CSP) of 22 secondary cities. Table 3 illustrates the 22 secondary cities provided by National Treasury. National Treasury used population and the size of the economy (GVA by Region) as the key indicators to identify the 22 cities as secondary. To present a more comprehensive picture of what constitutes a potential secondary city National Treasury individually profiled each of the 22 secondary cities using indicators derived from the international characteristics provided in Table 1. The outcome suggested that only the indicators listed below are considered pertinent when elevating cities as secondary in the South African context. The indicators are:
1. The size of a city's population—displays demographic strength as an important indicator of significance when contributing towards the country's national space economy—indicated by the number of people.
2. Population density—a key legislative criterion that defines whether an urban area is evolving into a more complex urban centre—indicated by the number of people per square kilometre.
3. The size of a city's economy—displays the role and contribution a city plays towards the country's national space economy—indicated by the city's GVA by Region.
4. Economic growth rates—display which cities are on a pathway of sustained economic success due to consistently recorded strong economic growth—indicated by the economic growth rate.
5. Personal income levels (per capita income levels)—a telling indicator illustrating whether a city is evolving into a stronger urban centre—indicated by the average income per person.
6. Municipal budget—to effect significant development changes and what reasonable proportion of its own revenue is generated by the municipality—i.e. own revenue generated.
7. Money a municipality spends on each citizen—displays how much a municipality has at its disposal to improve the lives of its citizens—indicated by the per capita revenue.
It should be mentioned that the international characteristics were only applied to the 22 cities and no other cities were considered. The eight metropolitan regions governed by metropolitan regions were therefore not considered.
4.2. Cooperative government and traditional affairs (CoGTA)
In moving beyond the City Support Program (CSP), CoGTA decided to develop a set of ICMs, which can constitute potential secondary cities. CoGTA also, for the same reasons as National Treasury, did not consider the eight metropolitan regions.
In developing the set of ICMs, CoGTA [32] considered more than 100 potential urban areas. In considering the potential urban areas CoGTA looked at 1) the size of the population in areas greater than 1,000 people per square kilometre and 2) how these relate to economic strength using Gross Domestic Product (GDP) as the basis, whereafter the urban areas were then ranked according to GDP. Following this, the urban size rankings were compared applying the following weightings: 1. Urban population and GDP ranking—equally weighted; 2. GDP ranking—weighted as twice urban population ranking (2 to 1); 3. Urban population ranking—weighted as twice GDP ranking (2 to 1); 4. GDP to urban population—weighted 1.5 to 1; 5. Urban population to GDP—weighted 1.5 to 1.
A methodology was then used to compare the various rankings in order to identify which cities scored highest on both the urban size and GDP—generally in the top 46. The cities that scored the highest, as illustrated by Table 4, were recommended as ICM or potential secondary cities.
4.3. Integrated approach
Marais and Nel [30] in their research, "Space and planning in secondary cities: Reflections from South Africa", focused on complexity as their theoretical foundation. Their research proposes that while there is no single definition of complexity, there is consensus on the features of complexity; the most notable being change. Complex systems are made up of many interacting elements or agents and can change and adapt over time, which aligns with Oranje, Meiklejohn and Van Huyssteen's [33] observation that the dynamic qualities of an area are developed historically and culturally over a duration of time. Complexity arises from interactions, and the interactions and their relationships determine the structure of the system, resulting in self-organisation. Self-organisation, on the other hand, enables the system to control itself, innovate, regenerate and adapt.
While CoGTA considered more than 100 potential urban areas, Marais and Nel [30] stayed with the quasi-list of 22 secondary cities provided by National Treasury. From the 22 cities, they selected 10 as part of a case study (see Table 5). For the case study, they focused largely on spatial changes and identified mechanisms that tend to influence these. For each of the 10 cities, they analysed policies (mostly Spatial Development Frameworks [SDFs]), conducted interviews (respondents from the public sector, business and civil society) and studied other relevant data (infrastructure access, housing, and population movements) on spatial change. They concluded that secondary cities are complex social and ecological systems with their own dynamic qualities, which correlates with Pumain's [34] submission that the spatial configuration of cities, their size and spacing, are the product of more or less constant processes whereby towns and cities are adapted to modifications and adjustments. Marais and Nel [30] did not develop a specific approach and yet, one can nonetheless surmise that spatial change or transformation measured against certain mechanisms or processes could be applied as potential criteria to identify secondary cities. In their case, they considered policies, the public sector, business and civil society opinions and other data such as infrastructure access, housing and population movements as key mechanisms when identifying secondary cities.
4.4. Population grid cells
Zimmer et al. [35] in their research on the dynamics of population growth in secondary cities across southern Africa, quantified the spatial distribution and temporal patterns of secondary urban areas in eight countries (Botswana, Lesotho, Malawi, Mozambique, Namibia, South Africa, Zambia and Zimbabwe) across the region between 1975 and 2015. To identify secondary cities, Zimmer et al. [35] followed a two-step approach, which was originally developed by Tuholske et al. [36]. First, urban area point locations were identified. Then grid cells with a population density of 1,500 people per km² or greater were created. Each of the grid cells was intersected with the point data to create an urban polygon. Each polygon was then augmented by adding adjacent grids that had a population density value of 300 people per km² or more. This allowed for the inclusion of adjoining suburban and peri-urban areas.
For the second step, the gridded population values within the urban areas were summed up to derive a total urban area population estimate. This was performed for each of the selected intervals between 1975 and 2015. A selection criterion on the 1975 population to include only those urban areas with populations between 500 and 100,000 was then imposed. This step eventually retained 629 urban areas that constituted secondary cities. From the 629 retained, 361 were identified as secondary cities belonging to South Africa (see Table 6).
The definition used by Zimmer et al. [35] of secondary cities is similar to those developed by Rondinelli [15] and Tuholske et al. [36]. Tuholske et al. [36] used 5,000 as a minimum population size, however, Zimmer et al. [35] consider a threshold of 500 to ensure that urban areas that by 2015 had populations larger than 5,000 are included. Furthermore, they used the maximum value of 100,000 to exclude larger urban areas, which they considered primary cities.
The above profiles perceived different prospects. National Treasury and CoGTA mainly focused on the population and economy sizes as the applied criterion. The integrated approach focused on mechanisms such as policies and interest groups' influences on spatial planning and what the intended and unintended consequences for spatial transformation are. Population grid cells focused on population density intersected with point data to create urban areas that were summed to derive a selection criterion at a specific interval that imposes urban areas with a population size across certain range values.
A potential critique would be that all four approaches worked on the assumption that cities under metropolitan management, or above a certain range value, are by default classified as a primary city, which brings forward the question raised by John [4] whether secondary cities are the same as an aspiring metro or do the two types of apexes offer different opportunities? The assumption also raises the question around the role of subjectivity, such as the role political interference plays in determining potential secondary cities, which in retrospect corroborate John's [4] notion that what constitute secondary cities in the South African context is hugely underdeveloped. The underdeveloped nature is further emphasised considering how the methods applied for each of the above profiles deviate from one another. In an effort to replace any potential consideration or method, the next section will focus on the role that interconnected regional networks can play as a potential unobstructed or differentiated approach to profile South African cities.
5.
Interconnected regional networks
Brand and Drewes [37] alluded to the notion that interconnected networks and the role that central functions play, are an important determining factor when establishing a city's place. The degree of variation between interconnected regional networks and the approaches presented above is based on the notion that cities are functional areas made up of multiple towns. This creates a spatial structure that allows for the broader inclusion of cities when establishing a city's place. Cities' proximity to one another or commuting distance establishes functionality, which allows cities classified at a lower order to be elevated into a higher order. In the development of a quantitative theory around the use of corridor development as a strategic and supporting instrument for the development of national space economies, Brand and Drewes [37] considered interconnected regional networks to measure the degree of interaction between cities. They concluded that the degree of interaction that also relates to complexity provides for a potential unobstructed approach to establish the place of a city within the overall hierarchy of cities.
Measuring the degree of interaction, as illustrated in Table 7, revolves around four key considerations. The first consideration establishes the general functional network of cities based on functional typology. It uses an Urban Function Index (UFI) as well as a city typology to determine the economic weight of urban settlements relative to one another, and to distinguish between the sizes of the commercial, service and industrial components of urban economies. In essence, it determines the relative economic dominance of cities in relation to one another. The second consideration converts, when considering synergy, the general network of cities into regional development nodes. Settlements have recently been linked to the daily and weekly urban system concepts advanced by Geyer and Geyer [38] and are used to quantify the relationships and flows (synergy) that exist between cities within a network. The outcome elevates cities, lower as well as higher order, into broader regional development nodes when consideration is given to the concept of synergy i.e. proximity—the commuting distance between cities—when establishing functionality of central places. The third consideration determines the degree of economic attraction or economic output exerted by each regional development node. The degree of economic attraction exerted by each regional development node is based on its economic weight, which is referred to as the Economic Impact Factor (EIF). The outcome elevates the status, or place, of the most dominant regional development nodes based on their degree of economic attraction exerted. The fourth consideration converts the network of regional development nodes into a functional index. The economic weight from the EIF provides for a natural break, which translates into a ranking score thereby allowing the opportunity to categorise each regional development node as either 1) mega, 2) primary, 3) secondary or 4) intermediate. The regional index in essence identifies a city's 'place' of functionality (performance) within a network.
Interconnected regional networks place a substantial focus on synergy, taking into account 1) proximity—the commuting distance between cities—when establishing functionality of nodes and 2) the degree of economic attraction or economic output levels exerted by regional nodes to elevate the status of a city. One can surmise that the main focus from a regional's perspective revolves around the association of cities in close proximity to one another when assessing their status, or place, from a synergetic apex (mega, primary, secondary or intermediate) i.e. individual cities at a lower order are elevated into a higher order when consideration is given to the concept of synergy. The key question is what permits the interconnected regional networks approach as a notable proxy for an unobstructed approach? Capello and Rietveld [39] analysed the concept of synergy and arrived at two distinct meanings, namely synergy is positive when two or more cities interact, or synergy is externally caused by individual cities that voluntarily, or non-voluntarily, form part of a group of cities. Therefore, as conceptualised by Meijers [40], the assumption is that cities in close proximity to one another relate to each other in a synergetic way making the whole network of cities more than the sum of its parts. The interconnected regional networks approach allows, through the concept of synergy, for the broader inclusion of cities, meaning it broadens the scope of individual cities to be classified as potential aspiring primate cities or aspiring secondary cities, which alludes to John's [4] question of whether secondary cities are the same as an aspiring metro or do they offer different opportunities?
6.
Conclusions
Although no specific criteria to distinguish the main characteristics of secondary cities exist it is evident that, irrespective of approach, population size and economic conditions are notably the main characteristics of central functions to determine a city's place within the overall hierarchy of an urban system. Delineating a city's role is important because it will enable government to fully exploit the development potential of a city, thus allowing government to target investment opportunities and structure economic conditions more strategically. Furthermore, the development of a national hierarchy of cities that defines each city's central function within the apex of hierarchies is critical. It can potentially create a realistic spatial perspective on long-term settlement patterns that can be used to transform socio-economic conditions at both primary and secondary level. It can also allow cities to identify opportunities that align with their circumstances, i.e. cities classified as secondary may respond proactively and innovatively to rapid change; realise their economic potential as a consumer, producer, landowner and investor to develop and promote themselves as an aspiring metro or aspiring primate city. Crucial in this context, however, is spatial development policy that supports the aspiring secondary city through relevant incentives. One of the primary reasons secondary cities are identified, is based on the principle that developing countries cannot develop all non-metropolitan towns and cities simultaneously. Accordingly, appropriate policy measures must be considered in support of this delineation process.
Lastly, the key question is which of the above-mentioned representations are considered most fitting when identifying the secondary status, or place, of a city? One can argue that all of the representations are a favourable option to consider, however, it should be emphasised that only the CoGTA and interconnected regional networks approaches considered a ranking score index to classify the secondary status of a city, which allows for a greater degree of objectivity. The main differences, however, allude to the notion that from all the potential approaches discussed, only the interconnected regional network approach allows, through the concept of synergy, for the broader inclusion of cities, which in essence broadens the scope and potential of individual cities as either mega, primary, secondary or intermediate. Lastly, the interconnected regional networks approach also diminishes the notion that metropolitan regions governed by metropolitan regions are by default considered primary cities.
Conflict of interest
The authors declare no conflict of interest.
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