Friday, 27 May 2016

City Footprints

Earlier in the week I posted a map of London's 'economic hinterland' on Twitter because I've been working with commuting data and wanted to see what the economic footprint of London looks like. But, some people have been telling me that other cities exist - which is a fair point. Since I have the data and I'm just revising a paper on the topic I thought I'd look at a few others, but this time using lower level data - MSOAs instead of districts for the origins. The maps below show the proportion of people from an MSOA who commute to a given area. Only MSOAs with 1% or more going to a particular place are shown and the darker the colour the higher the percentage. These aren't exactly the same as travel to work areas but they do give a reasonable approximation of each city's economic footprint. As you can see, I did quite a few maps - click to enlarge, as ever.

Birmingham has quite a pleasing concentric pattern

Bradford has quite a wide footprint

Bristol - quite a neat footprint

Cambridge is a little wider than I expected

Camden - one of a few London Boroughs I looked at

Cardiff - clearly the major focus in South Wales

Cheshire West - I wanted to see how far into Wales it goes

Derby seems relatively tightly packed

Leeds - the second largest local authority by population

Leicester - another quite tight East Midlands labour market area

Liverpool - extends into Wales and south to Cheshire, as you'd expect 
Greater London - the light areas are only 1% of commuters, but still!

Greater London - same as above, but with some city labels

Manchester - only the 'underbounded' district here, but still dominant

Middlesbrough - an important northern labour market area

Milton Keynes - I think it has quite a wide footprint

Newcastle - clearly dominant in the North East

Norwich - a good example of a large regional labour market area

Nottingham is relatively symmetrical in labour market terms

Oxford - a relatively large footprint here

Plymouth is a major South West economic zone

Reading - I had expected this to be a little bigger

Sheffield is another major northern labour market area

Southampton - somewhat overlaps with London's fringe

Southwark - I wanted to see how this London Borough looked

Swansea - quite a wide footprint here

Tower Hamlets - interesting to see the dominance of eastern origins

Warrington - a strategic hub in the North West

City and Westminster - the ONS group these two together

York - quite a wide Yorkshire footprint

Should I patch all these together in one big animated gif? Of course I should.

Why isn't my city included? Good question. Sincere apologies.

Birmingham doesn't get enough love, and is so often overlooked, so I did a zoomed in version of MSOA flows into Birmingham, with a few place labels.

Click here to see the full size version

Notes: the maps give the impression that they are unclassified choropleths, but that is just for effect and because this is a quick map batch. The colour classification is the same in each (see below) and no areas with less than 1% commuting to a given place are shown. I used the UK Data Service Flow Data website to extract the data and QGIS 2.14 for the maps. Bear in mind that they are a bit rough and ready and only really for comparison. Also, each 'city' here refers to the local authority area, not the wider city-region. But I think it's interesting to compare places. You just need to bear in mind the spatial scale and relative size of the destination places. Birmingham and Leeds ought to have much larger footprints that (e.g.) Nottingham and Sheffield because they contain more jobs. Where are Scotland and Northern Ireland? These datasets come separately and are not part of the English and Welsh MSOA geography so are not mapped here.

I used the same classification scheme for all maps