Heisei Municipal Mergers

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by Philbert Ono

During a period of seven years from April 1999 to April 2006, numerous cities, towns, and villages in Japan merged to form new or expanded cities and towns. During this period, Japan's number of municipalities shrank from 3,232 (670 cities, 1,994 towns, 568 villages) to 1,820 (779 cities, 844 towns, 197 villages). This is known in Japanese as "Heisei no Dai-gappei (平成の大合併)" (Great Heisei-Era Mergers). Heisei is the name of the current era based on the reign of the current Emperor Akihito since 1989.

Cities have merged with or absorbed neighboring towns and villages, and neighboring towns and villages have merged to form new cities. These mergers have rendered most maps of Japan obsolete, especially the prefectural maps showing city/town/village boundaries. This past seven years must have been a nightmare for map makers as many prefectures saw a new municipality being formed every couple months.

Business cards, rubber stamps, pamphlets and brochures, Web sites, and everything else bearing an address had to be corrected to reflect the new place names. Web site URLs of the old municipalities had to be redirected. It was almost like when the Japan Post Office revised and expanded its postal codes (zip codes) in 1998, affecting almost all Japanese addresses.

At the same time, some sadness is felt as the place names people grew up with are no more. Also, some public servants, especially local politicians, have lost their jobs.


Japan has undergone three major municipal mergers and realignments since the feudal era ended in the late 19th century. The first was the Meiji Mergers instituted in 1889 to convert and reduce over 71,000 feudal domains into over 15,000 modern-age cities, towns, and villages. Then in the 1950s, the Showa Municipal Mergers reduced over 9,000 municipalities to over 3,400. Many villages became towns during this time.

The Heisei Municipal Mergers took it to the next step, giving many towns the chance to become cities, and cities to become bigger cities by absorbing or merging with neighboring municipalities. The minimum population level required by law to become a city was temporarily lowered from 50,000 (set by the local government law in 1947) to 30,000 in the year 2000 to promote more mergers. The first city to take advantage of this lower minimum was Itako, Ibaraki Prefecture formed on April 1, 2001 with a population of 31,797.

The main reasons behind the Heisei Mergers are as follows:

  1. To promote further decentralization of government.
  2. To cope with the declining birthrate and aging population.
  3. To cope with falling tax revenues and subsidies from the central government. If the population is too low, it cannot support its local government.
  4. To streamline local governments with fewer government employees and share more public facilities.

Many merging municipalities were motivated to meet the central government's deadline of March 31, 2006 (as stipulated by the Special Municipal Merger Law) for merging to ensure that tax subsidies would continue to be received from the central government at the same level for another 10 years. Municipalities which do not merge before this date may see their subsidies from the central government gradually decrease.

Merged municipalities will also be eligible for construction subsidies from the central government which will bear up to two-thirds the construction cost of public buildings built during 10 years after the merger.

So the mergers really boil down to money, or the lack of it. This is not much of a problem for municipalities with a large population (such as in Tokyo where only 2 cities merged) or a steady source of tax income from well-established, local industries. Such municipalities have tended not to merge. There are also many cases where proposals for mergers were rejected because one of the municipalities was too much in debt. It is understandable for not wanting to marry someone deep in debt.

Other mergers did not go through due to disputes in the proposed new name of the new municipality. And of course, some municipalities did not want to merge because the mayor and his administration might lose their jobs.

Most of the mergers occurred in the rural areas many of which are seeing depopulation and decreasing tax revenues. There are still a few hundred municipalities with a population of less than 10,000. And over a hundred municipalities are still mulling over a merger. Indeed, there are many towns which you think should have merged with a neighboring city, but did not. There are even municipalities having two or more separate areas divided by a different municipality in-between.


  • The first municipality kicking off the Heisei mergers was the new city of Sasayama in Hyogo Prefecture formed on April 1, 1999 after four towns merged.
  • The city of Takayama in Gifu Prefecture is now Japan's largest city area-wise with 2,179.35 sq. km. This is bigger than the entire prefecture of Osaka (1,892.86 sq. km).
  • Tokyo Prefecture saw only one municipal merger with Tanashi and Hoya cities merging to form Nishi-Tokyo city.
  • In Ehime Prefecture, all municipalities except two towns underwent some kind of merger. Hiroshima and Shimane Prefectures also saw almost all their municipalities merging.
  • The Heisei Mergers also produced many more new city names spelled only with katakana characters such as Saitama-shi in Saitama Pref.
  • Hiroshima city is no longer Japan's largest producer of edible oysters. This title now belongs to Etajima city in Hiroshima Pref. as a direct result of its municipal merger.
  • The last municipality taking part in the Heisei mergers was the city of Yatomi in Aichi Prefecture absorbing a town and village on April 1, 2006.
  • Several hundred towns and villages in Japan with a population below 10,000 still exist. They are being encouraged to merge.
  • The merging of prefectures, such as those in Tohoku, is likely to occur as the next major municipal merger.

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