Japan's first City Planning Law and an accompanying Urban Buildings Law, both of 1919, created a national framework for designating planning areas, zoning land by use, and carrying out land readjustment to convert farmland into serviced urban plots. The system was strongly centralised, with the national government approving local plans, and it relied heavily on land readjustment to rebuild after disasters and to lay out new districts. A comprehensive revision in 1968 decentralised authority to prefectures and municipalities, introduced an urbanisation-control distinction between areas to be developed and areas to be preserved, and strengthened development permission. The law remains the backbone of Japanese urban planning.
It established the legal machinery, especially land readjustment and use zoning, that has shaped the rapid and disaster-prone growth of modern Japanese cities for over a century.