難波の南蛮、戎橋の夷。

Mapping Japanese City Spaces: Introduction

I may not have mentioned my interest in cities before.  I’m especially interested in the population changes of Japanese cities, and their changing urban space.  It’s become something of a hobby, and I’ve recently finished a project to calculate the urban populations of Japan’s metropolitan areas since 1960 and map them.

I’m using the Tokyo University Center for Spatial Information Science’s definition of a metro area as an employment area, where at least 10% of all the working residents of each city in the area commute to the core city.  For a more precise definition, see http://www.csis.u-tokyo.ac.jp/UEA/index_e.htm .  It’s a definition that reflects not just how many people are living in close proximity around a core city, but the degree of that city’s influence over the surrounding region, and the degree to which infrastructure has connected the region.  In a sense, a measure of that city’s prosperity.  It’s an organic definition, as the extent of a city’s urban area will change based on the quality of the economy and infrastructure, as more or less people commute there.  It’s a precise definition, calculated municipality by municipality rather than automatically declaring an entire county en bloc the metro area of its largest city, as in the United States census.

It’s also a very transparent definition; anyone who has access to the raw information can replicate the calculations.  The Japanese census is every five years, and Tokyo University has calculated the extent of Japan’s urban areas for 1980, and 1990-2005.  But since the census started consistently tracking commuter figures in 1960, it’s possible to fill in the university’s gaps.  That’s precisely what I’ve done, poring through volumes of census publications at the Osaka Central Library.

But I’m not interested in the total population of a metro area, so much as its urban population- the portion of the population that lives in denser, built-up blocks.  This is especially important in Japan.  In many countries, borders are drawn by county, survey township or region, with municipalities carving out their own borders when they incorporate.  This means there are large land areas outside of incorporated municipalities.  In Japan, though, all populated areas are incorporated by default- meaning that all land in Japan falls within the border of some city, town, or village.  This also means that many cities have large non-urban components: rural outskirts or outright unpopulated wilderness, included in the city because by law the land has to be part of some municipality.

The Japanese census started tracking urban populations in 1960 with the Densely Inhabited District (DID), a spatial definition of at least 5,000 people living together in an area with a density of at least 4,000 per square kilometer, plus any other adjacent built structures like offices, factories, or port facilities.  This handily shows what portion of a given city is the actual city, and what portion is non-urban.  Putting those two together- the DID population of an employment area- gives what I think is the best definition of urbanized areas in Japan.  I have calculated these for all of the country, for every census year since 1960 when this sort of data first became available.

 

Some basic trends emerge from all this:

In 1960, urban space was far denser in population that it is now.  Many city spaces actually still reflected the shape of Edo-period towns, grouped around castles, historic port districts, or old feudal roads.

Through the 1960s and 70s, urban spaces sprawled outwards rapidly, increasing in population but decreasing in density.  Suburbs and satellite towns emerged around major cities, the rapid development of formerly rural land.  The largest cities actually began losing population to their suburbs, especially in central neighborhoods which “hollowed out”.  The extent of employment areas increased as well, with many cities of all sizes growing in regional influence and “taking over” formerly independent neighboring towns as commuter towns.

By 1980, most of the major suburban expansion had run its course.  Through the 1980s and 90s, expansion and sprawl continued at a much smaller scale.  Most urban area increase came from employment area expansion, as cities “took over” independent towns and even other regional cities at an accelerating pace.

From 1995, new trends have emerged.  Population stagnation and loss is becoming more widespread.  Formerly affecting remote urban areas, it is now apparent in regional cities and even some major areas.  At the same time, the largest urban areas are actually accelerating in growth and re-centralizing as people move back into the dense city centers in large numbers.  Employment area expansion continues apace, as even regional cities that are losing population continue to grow in influence.

Interestingly, the top 10 urban areas haven’t changed that much since 1960, consisting of all the same cities in slightly different order.

1960 JAPAN
************
Tokyo-Yokohama-Kawasaki     12,237,406     1st
Osaka                                               5,437,788     2nd
Nagoya                                             1,607,591     3rd
Kyoto                                                1,281,016     4th
Kobe                                                 1,086,469     5th
Yahata-Kokura-Moji                       889,078     6th   (merged to create the new city of Kitakyushu in 1963)
Fukuoka                                             565,394     7th
Sapporo                                             496,302     8th
Hiroshima                                        455,598      9th
Sendai                                                357,559      10th

2010 JAPAN
************
Tokyo-Yokohama-Kawasaki     31,331,790     1st       + 156.0%
Osaka-Sakai-Higashiosaka        11,199,167     2nd     + 106.0%
Nagoya-Komaki                           4,279,800     3rd      + 166.2%
Kyoto                                              2,333,092     4th      + 82.1%
Sapporo-Otaru                             2,184,387      5th      + 340.1%     + 3 ranks
Fukuoka                                         2,135,871      6th      + 277.8%     + 1 rank
Kobe                                               2,129,951       7th      + 96.0%       – 2 ranks
Sendai                                            1,206,718      8th      + 237.5%     + 2 ranks
Hiroshima                                     1,177,199       9th      + 158.4%
Kitakyushu                                   1,048,163       10th    + 17.9%        – 4 ranks

Note the increase in rank of Sapporo, Fukuoka, and Sendai.  Kitakyushu, an industrial city in Fukuoka Prefecture, has been stagnant over the past few decades, and Kobe has not declined so much as simply been overtaken.

 

Nationwide, the cities with the most growth since 1960 are industrial and research cities in Aichi Prefecture and the northern Kanto region.  The cities with the most decline are mostly coal-mining cities in the interior of Hokkaido and Fukuoka Prefecture.  It is possible the population decline of the coal-mining regions is tied to the rapid growth of Sapporo and Fukuoka, as people from mining communities moved to the big cities for opportunity after the mines began to close.  It’s just a guess, though.

That’s a lot for just an introduction, but don’t worry.  Subsequent posts will have tons of pictures too.  I’ll be illustrating the elapsed changes in various urban areas and populated regions.

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