Following Milton Friedman's suggestion that economic models be judged not by the plausibility of their assumptions, but by their ability to predict, Queen Elizabeth asked some of LSE's finest why they did not see the Great Recession coming. Ouch!
In "The growth of cities," Gilles Duranton an Diego Puga make use of urban economists' "monocentric" model of cities for the obvious reason that it is analytically tractable. Citing the Glaeser and Kahn (2001) finding that "In 1996 only about 25% employees in US metropolitan areas worked within five km of the CBD ..." (p. 5), Duranton and Puga go on to say that there is, nonetheless, "strong empirical support for the existence of declining gradients of land and housing prices, population density and intensity of construction as predicted by the monocentric model." There are of course many other assumptions (homogenous labor and capital stock!) that cause concern.
I often cite Bumsoo Lee's work on the location of jobs in U.S. metropolitan areas in this connection (the paper has my name on it but this part is Bumsoo's work). They key table is reproduced below.
There are always debates on how "sub-centers" "central business districts, CBD's" etc. should be defined and delineated. Bumsoo tested two approaches and came up with roughly similar results. Average "big-city" CBD employment was either 7.1% or 10.8% of the metropolitan total. Take your pick.
Stick to the largest MSAs for the moment. Bumsoo found that 15% of the jobs were in subcenters and 78% were "dispersed". Let's talk about measured gradients emanating from the CBD. The measured density (for example) at any location is the vertical addition (density on the vertical axis, distance from the center on the horizontal) of all of the (
But a bigger point has to do with the fact that the survival (and growth) of any and all centers has to do with the agglomeration opportunities they offer. Agglomeration opportunities are apparently available at many places outside the traditional center.
Employment
shares by location type in 2000
MSA
Name
|
Employment
|
No. of
|
Employment
|
Share of employment (%)
|
|||||
Sub-
|
CBD
|
Sub-
|
Dis-
|
All
|
CBD
|
Sub-
|
Dis-
|
||
centers
|
centers
|
Dispersed
|
centers
|
centers
|
Perse
|
||||
A
|
B
|
C
|
|||||||
New York
|
9,418,124
|
33
|
937,055
|
1,057,297
|
7,423,772
|
21.2
|
9.9
|
11.2
|
78.8
|
Los Angeles
|
6,716,766
|
53
|
190,100
|
1,931,988
|
4,594,678
|
31.6
|
2.8
|
28.8
|
68.4
|
Chicago
|
4,248,475
|
17
|
297,755
|
504,732
|
3,445,988
|
18.9
|
7.0
|
11.9
|
81.1
|
Washington
|
3,815,240
|
16
|
283,341
|
449,488
|
3,082,411
|
19.2
|
7.4
|
11.8
|
80.8
|
San Francisco
|
3,512,570
|
22
|
205,553
|
849,021
|
2,457,996
|
30.0
|
5.9
|
24.2
|
70.0
|
Philadelphia
|
2,780,802
|
6
|
239,735
|
125,190
|
2,415,877
|
13.1
|
8.6
|
4.5
|
86.9
|
Boston
|
2,974,428
|
12
|
238,092
|
239,257
|
2,497,079
|
16.0
|
8.0
|
8.0
|
84.0
|
Detroit
|
2,508,594
|
22
|
129,845
|
557,776
|
1,820,973
|
27.4
|
5.2
|
22.2
|
72.6
|
Dallas
|
2,565,884
|
10
|
126,010
|
404,365
|
2,035,509
|
20.7
|
4.9
|
15.8
|
79.3
|
Houston
|
2,076,285
|
14
|
165,525
|
432,101
|
1,478,659
|
28.8
|
8.0
|
20.8
|
71.2
|
Atlanta
|
2,088,215
|
6
|
166,946
|
223,168
|
1,698,101
|
18.7
|
8.0
|
10.7
|
81.3
|
Miami
|
1,623,892
|
6
|
121,045
|
243,970
|
1,258,877
|
22.5
|
7.5
|
150.
|
77.5
|
Seattle
|
1,745,407
|
7
|
163,051
|
207,542
|
1,374,814
|
21.2
|
9.3
|
11.9
|
78.8
|
Phoenix
|
1,463,581
|
9
|
104,417
|
189,071
|
1,170,093
|
20.1
|
7.1
|
12.9
|
79.9
|
3 million and plus
|
17.0
|
22.1
|
7.1
|
15.0
|
77.9
|
||||
1 to 3 million
|
2.6
|
17.8
|
10.8
|
7.0
|
82.2
|
||||
half to 1 million
|
0.9
|
17.4
|
12.2
|
5.2
|
82.6
|
||||
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