On Tuesday, we ran an article on Alasdair Rae's maps of English urban areas, in which we examined the different levels of coherence visible in different metropolitan regions.
What we ignored, though, is that the four northern areas are actually adjacent to one another. In some ways they make up a single urban region, stretching across the Pennines from Liverpool to Wakefield: the multi-centred urban belt that George Osborne is hoping to turn into his "northern powerhouse".
Rae's data was in distinct metropolitan chunks so we've combined them ourselves. The results are no doubt imperfect (and if you spot any major clunkers we're happy to amend), but you get the idea:
This complicates the idea of city regions even further. That blue blob is the town of Hebden Bridge which, officially, is part of West Yorkshire. Look at the region as a whole, though, and it's not obvious it “belongs” to Leeds any more than it belongs to Manchester (thanks to a direct train line, residents commute to both). Once again you can see quite how hard it is to draw a line around an area and say “this is an English city”.
UPDATE: Dr Rae has since been in touch on Twitter to point that he, er, had already done this properly. We're leaving our version in place, if only because it took ages, but his is very obviously better, not least because it includes local authority boundaries, enabling you to see the shape of the region much more clearly. Here it is:
There’s one other thing to notice about this map. The combined population of this northern belt is around 7.6m, and their combined area is 5502km2: that gives the region a population density of around 1381 people per km2.
Greater London fits around 8.6m people into less than a third of the area (1569km2): a population density of 5481 people per km2.
This is probably pretty much what you'd expect, but nonetheless, it's worth hammering home. To emphasise quite how much more densely populated London is than the trans-pennine belt, we've shoved the four northern metropolitan counties together into a single lump, and placed them next to the capital:
We often say we could easily accommodate more people in London if we felt the need. That's true. But it's even more true of the north.