Urban system is the special manifestation of political economy and the land management method of a country. The manner of distribution and the level of balance of the cities’ population get clearer by examining the urban system. The urban system of Iran tended to change from the traditional pattern before 1921 because of the centralization of facilities and services in big cities. This pattern distracted the logical relationships among small, medium and big cities and led to disorder in the urban system. The research purpose is to assess the Iranian urban hierarchy based on population during the period of 1956-2012. To measure the urban hierarchy, the Entropy coefficient, the rank-size rule, the primate city- Lorenz curve and Gini coefficient were employed. The statistical data cover all cities of Iran in six census periods. The findings of the current study show that the urban system is becoming more balanced with regard to the indices of concentration coefficient, rank-size, primate city, and entropy index; but with regard to Gini Coefficient and population distribution in urban classes, there has been an imbalance compared to the situation in 1956. In fact, according to the Lorenz curve, the Iranian cities have been near the normal line in 1956 but got away from this line in 2012. This is because of the increase in number of small cities with little population and the increase in population of big cities. To reach a balance in urban system of Iran, strategies to decentralize metropolises and boost small and medium-sized cities are suggested.
