2013-05-17
post/50674912131
Not to be confused with: a social gathering of invited guests, typically involving eating, drinking, and entertainment: an engagement party. ”
2012-03-13
The Sizes of Cities
What’s the largest city in the world? This seemingly simple question is actually rather complicated to answer. In my post Concentric Londons, I noted how you can define the city in various ways (and I still missed a few), while my complaints about the interesting but flawed visualisation showing “how much room would you need for the world’s population if the city were as dense as…” noted that the cities picked were defined very differently.
It turns out that the BBC’s excellent More or Less tackled the issue in a special edition, which (thankfully) is also available as a BBC News Magazine article (for those of us who prefer reading words to hearing them). After noting some of the problems I’ve covered - is a city the same as the government region defining it, or is it a contiguous urban area, or perhaps a zone of influence? - they settle on Tokyo/Yokohama, at 30 million plus, as the most reasonable answer to the question.
Curiously, it turns out that there is no official UN (or other reliable worldwide) definition of a city. Where Paris excludes its periphery, London extends nearly to the M25; where New York excludes Jersey City, Greater London expanded in the 1960s to swallow chunks of Essex. That’s not even to consider cities such as Cairo, Nairobi, or Rio de Janeiro, where informal building means a density and sprawl that’s a laissez-faire economist’s dream.
However, that wasn’t the end of the show. The final section covered China’s cities, which, if you believe the numbers, are growing like nothing on earth. However, the numbers may not be that trustworthy. Official statistics, as noted by guest Professor Kam Wing Chan, conflate cities with provinces, which can be largely rural, inflating estimates by as much as a factor of five:
The largest city in China is actually Shanghai. It is commonly thought to have a population of 20 million, but Professor Chan thinks 16 million is a better estimate.
He says everyone just loves to think China’s cities are bigger than they actually are. He has even had to correct fellow experts at a world conference on global megacities of the future.
One thing’s for certain: you can’t take the numbers at face value.
2011-03-23
post/4038393782
“If the world’s 6.9 billion people lived in one city, how large would that city be if it were as dense as…”
When I first saw this map, I was slightly peeved that London appeared to have lower density than San Francisco, or Paris. I lived in London for ten years, and have been in SF for a few months. I hope residents of the latter won’t be too offended if I say that, all too often, even relatively central neighbourhoods feel more than a little suburban.
I decided to go and have a deeper look at the figures. Firstly, at the original post, Tim De Chant (who designed the maps), writes that they’re based on
Strictly city limits. So the San Francisco map, for example, only uses density data for the city of San Francisco and does not factor in Oakland, San Jose, etc.
Now, San Francisco is a city of 600 km², with a population of roughly 800,000. It’s embedded in a larger “combined statistical area” - including the aforementioned cities - of nearly 8 million. The densities for the two? 6,688.4/km² and 320/km² respectively. There’s almost a factor of twenty difference there.
By contrast, London’s nearly 8 million fit into an area barely one-fifteenth that of the Bay Area - making the entire city nearly match San Francisco’s density. The central London boroughs - like Islington, where I lived for six years - come top of the list of districts by population density in the UK, with double the population per square kilometre of SF. (I haven’t bothered to calculate the density of the old LCC boroughs, but my bet would be they handily outrank SF, although I doubt they approach NYC.)
Similarly, the incredible showing by Paris is helped by the fact that the city is still defined by its medieval extent, excluding a large chunk of its metropolitan area: to paraphrase Wikipedia, the city has a population of two million, but the metropolitan area has a population of nearly twelve. The density of the latter is roughly one seventh that of the former - and lower than that of London of SF.
This is, perhaps, too much effort to put into a single graphic, especially one that does such a good job of showing how sprawling a car-centric US city can become (hello, Houston). However, it’s an interesting exercise in noting that defining a city is harder than it may appear.
2010-11-30
Concentric Londons
There are many concentric definitions of London. This probably isn’t an exhaustive list of the potential boundaries, but let’s give it a go. (For this version, there aren’t any links, nor are there maps. Consider this a work of geography, not cartography.)
Londonium
or, Roman London. Defined by London Wall, the remains of which are still visible. Tiny, but still more or less discernable.
The City Of London
Historic, rich, and a strange sort of local authority, the City is (just over) a mile square (hence its nickname) on the north bank of the Thames (although it maintains four road bridges, and one footbridge). Find its boundaries by looking for griffins on poles.
The Cities of London and Westminster
Combine the old centres, which meet on the Thames, and you have this double-headed beast (and parliamentary consitituency, although excludes the northern part of the Borough of Westminster).
The Inner Ring Road
A selection of numbered roads provides the boundary for the central Congestion Charge area, and one definition of “central London”.
The Civil War Defences
Built in 1642 to defend the Parliamentary capital, 11 miles of wall take in an area from Shoreditch to Hyde Park, and Vauxhall to Rotherhithe.
Zone 1
Transport for London’s central fare boundary, which reaches a bit beyond the ring road. Of course, with nine zones, there are further boundaries outside this one, useful for bragging rights (and saving money on a Travelcard).
071
In 1990, Ofcom broke London’s old 01 telephone code in two, introducing 071. After two more changes, the city now has a single area code, 020, but there’s still plenty of numbers (and people who’ll remove the space) to testify to the old distinction the between “inner” and “outer” codes.
Inner London
Originally defined in the Metropolis Management Act of 1855, finally given a sane system of government in 1889 (as London County Council) and lingering since 1965 as a definition for local government financing, these twelve modern London boroughs (and the City) form a large, but not all-encompassing, core.
Inside the Circulars
The North Circular, a hodge-podge of custom-built dual carriageway and converted streets, and the South Circular, which is barely a trunk road at all, form a ring around a certain definition of the place.
The London Postal District
Taking in eight postcode areas, this area’s been slowly contracting for years. Even bits of TfL’s zone 4 are outside it.
020
The larger, current, telephone code for London, which manages to not match the legislative boundary at all.
The Green Belt
Aimed at ending sprawl after the war, the green belt more or less worked. Its inner boundary stopped London’s expansion (especially in the north-west, where the Tube was once to have been extended.)
Greater London
Defined in 1963, made a council in 1965, and currently the area that elects the London Mayor, eight MEPs, and 25 GLA members. This is the fuzzy shape most Londoners will recognise as a map of their city, I’d say.
The M25
Planned as part of the post-war London Ringway schemes, mangled to fit, and labelled the Road to Hell, the London Orbital - 120 miles long, and roughly 15 miles from the centre - is a usefully physical boundary to the city.
TfL Zone 9
You can get outside the M25 by Tube, even without going to zone 9 (Epping, on the Central Line), but by going into the strange new zones that used to be letters, you can get a long way north-west, into the wilds of Buckinghamshire.
Travel to Work Region
London’s economic impact sprawls well beyond any of these relatively well known (if messy) boundaries. A map drawn to define an area such that it contain 85% of those working within it reaches the Essex coast, nearly to Cambridge, and most of the way to Brighton. Similarly, one that allows up to 25% of people to be commuters draws in districts up to 30 miles away.
After that, London’s influence bleeds away, to be submerged in the rest of the south east.
(This is a response of sorts to Oliver O’Brien’s piece, Where is London?)
