One way to define an urban settlement is to use its existing administrative boundaries, and these are areas defined by city, town, or borough councils. The disadvantage of this method, which was used in the national census, was that the administrative boundaries were rarely changed by councils, and therefore did not reflect the rapid development of many urban settlements. There are at least three other methods of defining an urban area, however. The first is defining the size of the built up area (the bricks and mortar approach). The second method is defining an urban area by the facilities and services available to the local population, known as the functional area. The functional area not only includes settlements in the built-up area but also free-standing settlements outside of the built-up area, settlements that have access to the facilities and services of the local urban area. The third method used to define an urban area is to use density, of either population or buildings, as an indication of urbanization. The downside to all these methods is the fact that some arbitrary decisions as to the boundaries between towns will have to be made, because the reality is that many towns and large settlements have already merged together, creating one large urban area, making these methods redundant.
             Urban fringes come under attack at times of economical growth in a country. An example of this is Japan, and its capital city Tokyo, which experienced rapid migration in the years after world war 2, between 1950 and 1970. With rapid economic growth in the country, the focus on migrating to the cities became stronger, with higher incomes and a higher standard of living attracting more and more people from the poorer rural communities. With this increase in migration to the cities, the urban-rural fringes came under pressure to be urbanized to make space for the people who were migrating to the city to live in.
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