Dependence on maldistribution of world population
The population of the world is distributed very unevenly over the land mass. Approximately 90% of all people are crowded into no more than 25% of the land surface. Variations in population concentration are due to differences in natural or social conditions. Although the proportion of developed countries experiencing difficulties caused by the spatial distribution of their population is smaller than the proportion of developing countries, these difficulties nevertheless occur quite frequently. The industrial mobility necessary to the functioning of the economic apparatus constantly creates problems of adjustment. Some countries are also starting to show concern at the excessive depopulation of rural areas, which has reached its limit, while others must still cope with relatively large-scale migration from the countryside to the towns. The development of new urban centres and the decline and renovation of older ones also present problems for almost all governments. Lastly, problems of environmental protection add a new dimension to spatial distribution policies.