Tenured Professor at
The Open University of Japan

The Meshed Data to Define Geographical Extension of Urban Areas

The Statistics Bureau of MIAC(Ministry of Internal Affairs and Communications) has reorganized the results of the Population Census, the Economic Census and the Establishment and Enterprise Census into small regions of approximately 1 square kilometer and 500 square meters, dividing the whole area of Japan by latitude and the longitude (see Statistic Bureau: Grid Square Statistics). This is available as basic data for GIS (Geographic Information System) and promoted its use by Statistical Information Institute for Consultant and Analysis: 統計情報開発センター(Japnanese only）.

"The Grid Square Statistics are used not only for the numerical value but also with the background area information, to plan various administrative measures including regional development, city planning, transportation planning, countermeasures against pollution and natural calamities, life environment maintenance, etc."
(Statistic Bureau: Grid Square Statistics> Introduction)

The method of demarcation for the Standard Grid Square is as follows:
A Primary Area Partition is demarcated by 40 minutes of latitude and 1 degree of longitude. The Secondary Area Partition is demarcated by dividing a Primary Area Partition into 64 (8 by 8) equal parts vertically and horizontally, and the Basic Grid Square (Third Area Partition) is demarcated by dividing a Secondary Area Partition into 100 (10 by 10) equal parts vertically and horizontally. This Basic Grid Square is approximately 1 square kilometer, in addition 500m and 250m grid square data are also available.

Partition	Method of demarcation	Interval of latitude	Interval of longitude	Length of side	Relation with map
Primary Area Partition	Divide the country into some equal parts measuring 2/3 degree of latitude by 1 degree of longitude.	40 minutes	1 degree	about 80 km	One page of 1/200,000 Regional Map (published by the Geospatial Information Authority of Japan)
Secondary Area Partition (Integrated Grid Square)	Divide a Primary Area Partition into 64 (8 by 8) equal parts towards longitude and latitude.	5 minutes	7 minutes 30 seconds	about 10 km	One page of 1/25,000 Topographic Maps (published by the Geospatial Information Authority of Japan)
Basic Grid Square (Third Area Partition)	Divide a Secondary Area Partition into 100 (10 by 10) equal parts towards longitude and latitude.	30 seconds	45 seconds	about 1 km
Half Grid Square (Divided Grid Square)	Divide a Basic Grid Square (Third Area Partition) into 4 (2 by 2) equal parts towards longitude and latitude.	15 seconds	22.5 seconds	about 500 m
Quarter Grid Square (Divided Grid Square)	Divide a Basic Grid Square (Third Area Partition) into 16 (4 by 4) equal parts towards longitude and latitude.	7.5 seconds	11.25 seconds	about 250 m

(from Statistic Bureau>Method of Demarcation for Grid Square)