City size distribution evolution in Iran Urban system

Iran has beheld rapid urbanization since the Islamic revolution in 1978. Number of cities increased from 200 in 1956 to 1016 in 2006, while the urbanization rate increased from 31 to 69 percent. This study used Zipf’s law to investigate the Iran urban network changes during 1956-2006. Results showed that City-size dynamics in 1986-2006 periods has been decreased inequality in compare with the1956-1986 period. It could be concluded that there is a decrement Zipf index within Iran’s urban system and that the above mentioned changes in the “long decade of the 1978s” cause to increase cities number and enlarging other metropolitans except Tehran.
One of the main factors which are helping to balance the size-rank pattern of the cities in country is developing towns and cities because of existed problems and difficulties in metropolises and especially Tehran. Deduction process of population portion in metropolises and intense changes in economical, social, political and cultural structures cause an increase in immigration of people to towns and cities. Governmental support for towns and cities can be an effective step in balancing city rank chain of the country.