Commentators have long studied connections between cities and how these influence their development. The city is the natural focus of trade-based theories of growth. Exporting a surplus, based on local resources and specialisation was – and is – considered the way to city wealth.
In this world, transport is the key to the trade portal. The cities that dominated world trade in the 19th and 20th centuries were those best connected, initially through their ports and sea links complemented later through strong ties over the airways. Mega-ports and airport hubs were marks of city success.
This model may be changing, and we need to change our thinking about the future of our cities with it.
Connectedness and concentration
Connectedness is a mantra for the new urbanists: through international connection cities exploit the economies assumed to arise from ever-increasing concentration of people and business. Hence, the city seeking to make its mark globally must invest in ever increasing transport infrastructure. Acknowledging the information age, it may add high-speed broadband to the mix and perhaps, in a symbolic move, an international convention centre.
But is this the right model for 21st century urbanisation?
Aviation – moving on
Think for a moment about what has happened in aviation. The last decade saw a quantum shift from a model whereby a few powerful hubs concentrated movement between a few major centres from which passengers and goods could, in turn, be distributed along local spokes – by regional aircraft, train, coach or car. Airlines based themselves overwhelmingly at these hubs. The large, twin isle jet reigned supreme. The Airbus A380 is the latest conveyor of that model, but most likely the last.
Because late in the 20th century there was a divergence between an ageing hub and spoke model and a growing model based on dense networks connecting more and more cities directly. The single aisle, medium-haul jet took off. And now the long-haul, highly efficient, medium-sized jet is further expanding this capacity to directly connect former spokes – smaller cities – without the need to hub through major cities.
And all of this has been supported by the productivity leap brought about by the low cost airline model. More people, more cities, more directly connected than ever before with the capacity to transform economic, political and social relations among them. 
From transport to logistics
The transport sector was about moving goods from A to B as cost effectively as regulation allowed; and all too often regulation kept costs up to protect old technology and incumbent operators, whether by surface, air, or sea. That, though, is changing as international transport is liberalised.
And today transport is itself transforming into the business of logistics. And logistics is about distribution – through a production chain, between producers and consumers, and among places. Goods move seamlessly through integrated operations that can deliver almost anything almost anywhere in a matter of days.
An informational world
As the capacity to transport goods went up and the cost went down, academics trying to explain the differential growth of cities appealed to a new notion that dominating the exchange of information was the new key to prosperity. Knowledge and expertise were concentrated in key informational hubs where they became the centres of capitalist power, the hearths of globalisation. 
Well that’s changing, too. Information and expertise is becoming dispersed, knowledge ubiquitous. This is not just about the internet – although it obviously plays a huge part. It’s also about the explosion of personal mobility as informational cities give way to an informational world. (It may also be about the potential for implosion as a result of over-concentration, a threat still lingering in the financial centres of the world).
Linked cities are giving way to networked communities.
From consolidation ...
The lesson? Those of us involved in planning the city cannot assume the same structures will prevail in the future as those we inherited from the past. We tend to plan, though, by looking for repeat patterns, seeking generalisation, extracting principles, predicting the unpredictable. And because infrastructure – roads, rail, ports – are large scale, expensive, and enduring they become the bones around which we construct our futures.
Infrastructure, particularly transport infrastructure, shapes our presumptions about how the city will function and the form it will take. Hence, urban planning is preoccupied with how to consolidate existing structures, increasing their capacity by building up rather than out and moving to mass transit, among other things.
... to dispersal
Yet the shifts in 21st century logistics and information technology support dispersal. And it might just be that dispersal is the key to 21st century urbanisation.
Light rail systems, dedicated bus lanes, smaller, more fuel efficient vehicles, lower housing costs, more intimate localised but inter-connected sub-urban communities, common information and mobile expertise cutting across diverse tastes, experiences, and places – these may be the way of the future.
In the developing world where urbanisation is most rapid they may be the only way. Here dispersal is already the dominant reality. While urbanisation may be exemplified in a few megacities in Asia, these account for only a small part of the total. And even they are marked by rapid peripheral expansion, with distinctive, sprawling, dense and diverse communities on the edge. Democraticised, localised self help institutions and NGOs may be the way to improved sanitation and health care in this environment, and micro-commerce the way to sustainable prosperity.
And in the slower-growing cities of the west, the maturing of sub-urban life, a return to lifestyle-focused localism, ageing in place, and the growing importance of community-based care point to a future in which dispersal rather than concentration could be the dominant mode of social and spatial organisation. Central structures may still have a role, but a diminishing one.
More generally we may have to think of cities themselves as comprising networks of connections, within and across boundaries. The stronger these networks, perhaps, the more resilient the city. But this does not translate to physical density. Proximity is not the issue. Well connected, dense networks will support, if not encourage, dispersal.
This is contrary to the currently favoured model in places like my city of origin – Auckland – but it is not at all contrary to the centre within that city that I call home.
Getting it wrong
More than ever as we try to plan for the very long-term, we need to open our minds to alternatives. You only need to look at the list of bankrupt airlines (or in and out of Chapter 11 in the US) to appreciate the consequences of overinvesting in the current model on the assumption that it will prevail indefinitely.
Phil McDermott is a Director of CityScope Consultants in Auckland, New Zealand, and Adjunct Professor of Regional and Urban Development at Auckland University of Technology. He works in urban, economic and transport development throughout New Zealand and in Australia, Asia, and the Pacific. He was formerly Head of the School of Resource and Environmental Planning at Massey University and General Manager of the Centre for Asia Pacific Aviation in Sydney. This piece originally appeared at is blog: Cities Matter.
Aircaft photo by BigStockPhoto.com.
 See, for example, Centre for Asia Pacific Aviation (2003) Low Cost Airlines in Asia Pacific: A Force for Change and (2009) Global Low Cost Carrier Report
 E.g. Castells M (1990) The Informational City: Economic Restructuring and Urban Development Blackwell; Sassen S (1991) The Global City, New York, London, Tokyo, Princeton University Press