For a long time, I've been interested in the shape of cities and I suspect that if you're reading this you might be similarly afflicted. By 'shape' I mean their political boundaries as opposed to their general urban footprint. The latter can be seen by driving around or from a plane window, particularly when it's dark, but the political boundaries are much less obvious. This is particularly true of US cities. Take Houston, Texas - the first example below.
|The boundary of the City of Houston - Google Map|
Look closely at this and - at least if you're not used to the political geography of American cities - you might be very confused by this fragmented, segmented mess of boundaries. Then go to Google maps and try different search terms, such as 'city of los angeles' or 'city of columbus' (Ohio) and you'll soon discover that Houston isn't that unusual at all. Try it for other cities and you'll see what I mean. Columbus, Ohio is a particular favourite of mine as I know it quite well having lived there for a couple of years in the early 2000s.
|City of Los Angeles - Google Map|
|City of Columbus (Ohio) - Google Map|
These unnatural-looking boundaries are the result of a complex mix of geography, history and politics that have real impacts on the ground. From education and transport to housing and waste management, the shapes of cities really do matter in this respect. Of course, this is a much-studied topic in urban studies, not least by Professor John Parr of the University of Glasgow. In Parr's economic definitions of the city, he outlines four types - but none of these explain the kinds of boundaries we see above. One major explanatory factor in all of this, of course, is tax revenue. But I'm not going to get into that now because it opens up a whole range of other topics, including white flight, suburbanisation, and schooling, amongst other things. The point is that the 'shapes' of cities are not accidental and who is included or excluded is inherently political.
In the United Kingdom, we might not have such unusual city boundaries, but the political geography of our cities is far from perfect - perhaps one reason for the resurgence of the 'city-region' concept over the past decade or so. When we're talking about urban economies, it makes much more sense to think about the functional urban area than it does to use data associated with an arbitrary political shape. This is as true in the US as it is in the UK. The example below shows that the City of Atlanta has less people than the City of Liverpool and that it's only slightly bigger in scale. But anyone who knows anything about these places will understand that 'Atlanta' is much bigger than 'Liverpool and is vastly more sprawling, with a metropolitan population of around 5.5 million compared to less than a million in 'Liverpool' (by one definition).
|Atlanta vs Liverpool - which is bigger?|
These kinds of issues are part of the reason organisations like the Centre for Cities use the Primary Urban Area definition of cities for the 64 largest urban areas of the UK. In a recent study, I used a definition developed by Geolytix which is based on the 'sprawl' of the urban area rather than political boundary and found this to be a much better fit than the administrative area. When conducting comparative analyses of cities, we need to ensure we are comparing like with like, and using a functional definition often helps avoid the kinds of underbounded/overbounded problems that arise when (e.g.) comparing places like Manchester and Leeds. The former is normally said to be 'underbounded' because the functional urban area is much bigger than the local authority area of the same name and the latter is said to be 'overbounded' because of its much wider local authority area, which extends beyond the core urban fabric. For a comparison of UK 'city' sizes, see this graphic I produced a few years ago:
|All cities shown at the same scale|
Surely there's a point to all of this?
Yes, glad you asked...
For planners, politicians, residents and neighbours, the shapes of cities matter enormously. It might dictate which school your children can go to, whether your local facilities are well funded, whether you have a well-functioning local transport system, when your bins get emptied, how many pot-holes you have in your street and all sorts of other things. But let's not get into that now. Instead, I'll end with another city shape, this time for the City of Detroit (one of my favourite cities, but much-maligned).
|Detroit - 8 mile boundary line to the north|