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In this article, the effects of the physical development of Yazd City on the construction and variables of population in old texture and the
results acquired from this change have been scientifically investigated. The major aim of this study is to consider the undesirable effects of population caused as a result of irregular development and in congruence of Yazd City and the carelessness of internal sustainability development to reach this goal. The methods of descriptive analytical research have been used and the statistical data available in Iran
Statistical Center have also been applied. The results acquired show that the physical development and the irregular development of the city have been the major factors of the displacement of population, and consequently cause the changes of population structure in the old and new sections.