Taiheiyō Belt

File:Pacific ocean belt map common.png

A map of the Taiheiyō Belt showing the Tōkaidō and Sanyō shinkansen routes.

The Taiheiyō Belt (太平洋ベルト, Taiheiyō beruto, lit. "Pacific Belt"), also known as the Tokaido corridor, is the name for the megalopolis in Japan extending from Ibaraki Prefecture in the north all the way to Fukuoka Prefecture in the south, running for almost 1,200 km (750 mi).

The urbanization zone runs mainly along the Pacific coast (hence the name) of Japan from Kantō region to Osaka, and the Inland Sea (on both sides) to Fukuoka, and is concentrated along the Tōkaidō-Sanyō rail corridor. A view of Japan at night clearly shows a rather dense and continuous strip of light (demarcating urban zones) that delineates the region.

The high population is particularly due to the large plains – the Kantō Plain, Kinai Plain, and Nōbi Plain – which facilitate building in mountainous Japan. Coastal regions are at high risk of earthquakes and tsunamis, due to the nearby Nankai Trough (Nankai megathrust earthquakes) and Sagami Trough, notably the 1923 Great Kantō earthquake, and further damaging earthquakes are expected in the region; the combination of population density and seismic activity is responsible for the high-impact earthquake and tsunami risk in Japan.

Although it contains the majority of Japan's population, references to it in Japanese are mainly economic or regional in nature. The term was first used in 1960 in an Economic Commission Subcommittee Report formed to double the national income. At that time, it was identified as the core of the nation's industrial complex. Other than the Miyagi area damaged by the 2011 tsunami, nearly all manufacturing industry in the nation lies in this zone, accounting for 81% of the nation's economic output in 2007 (about 4-5 trillion USD).

The region is specifically defined by the Ministry of International Trade and Industry as the following prefectures: Ibaraki, Saitama, Chiba, Tokyo, Kanagawa, Shizuoka, Aichi, Gifu, Mie, Osaka, Hyogo, Wakayama, Okayama, Hiroshima, Yamaguchi, Fukuoka and Oita. As economic development (along with urban development) spilled over to nearby regions, they were added to this list.

The Sea of Japan has a much less well-developed string of cities, called, very pejoratively Ura-nippon (裏日本) (literally: the back of Japan), stretching 1000 km from Akita to Yamaguchi. It is often referenced in relation to the Taiheiyo belt. The Shinkansen line south (and west) of Tokyo runs the course through the belt cities.

Major cities

A nighttime satellite photo comparison (to scale) of the Northeast Megalopolis in the United States (top) and the Taiheiyō Belt (bottom).

Listed from north to south:

city	including	population
Greater Utsunomiya	Nikkō, Kanuma, Tochigi, Oyama, Shimotsuke	900,000
Greater Maebashi	Takasaki, Kiryu, Isesaki, Ota, Ashikaga, Sano, and Tatebayashi	1,500,000
Greater Ibaraki	Mito, Tsuchiura, Hitachinaka, Hitachi, Tsukuba	1,300,000
Greater Tokyo		35,500,000
Mt. Fuji Area	Gotemba, Atami, Numazu, Fujinomiya, Fuji, Mishima	700,000
Greater Shizuoka		1,000,000
Greater Hamamatsu	Kakegawa and Iwata	1,100,000
Toyohashi		400,000
Greater Nagoya (Chūkyō Metropolitan Area)		8,000,000
Greater Osaka	Osaka, Kyoto, Kobe, Sakai, and Higashiosaka	17,000,000
Greater Nara		1,000,000
Himeji		500,000
Tokushima		300,000
Greater Okayama	Okayama, Kurashiki, Takamatsu, Marugame, Sakaide, Tamano, Soja	1,900,000
Fukuyama-Kure	Onomichi, Mihara, Higashi Hiroshima	1,100,000
Greater Hiroshima	Hatsukaichi	1,300,000
Greater Matsuyama	Imabari, Saijō, Niihama, Shikokuchūō	1,050,000
Iwakuni - Yamaguchi	Ube, Hofu, Shunan, Hikari, Sanyō-Onoda	1,000,000
Kanmon Straits	Shimonoseki and Kitakyushu including Iizuka	1,700,000
Greater Fukuoka	Saga and Kasuga	2,500,000
Kurume		300,000
Nakatsu		215,000
Oita	Beppu	700,000
total population		83,000,000

May also include:

city	including	population
Kumamoto	Kumamoto and its surroundings	1,600,000

See also

• List of metropolitan areas in Japan by population