Tehran, the capital, is the country's largest city and the second most populous city in the Middle East after Cairo. Tehran is a comparatively young city, the origins of which date back about 700 years. The old part of the city is a few kilometers to the northwest of ancient Rey, an important city that was destroyed by the Mongol invasions of the thirteenth century. Tehran was founded by refugees from Rey, but remained an insignificant small town until the end of the eighteenth century, when the founder of the Qajar dynasty chose it to be his capital (see The Qajars, 1795-1925 , ch. 1). Tehran has been the capital of the country ever since.

The centralization of the government and the expansion of the bureaucracy under the Pahlavis, the last royal dynasty, were major factors in Tehran's rapid growth after 1925. The city's population doubled between 1926 and 1940 and tripled between 1940 and 1956, when it reached more than 1.5 million. Tehran's population continued to grow rapidly, exceeding 2.7 million by 1966. Its population in the 1986 census was slightly over 6 million. This figure represented a 35 percent increase over the 1976 census of slightly under 4.5 million.

In 1986 Iran had one other city, Mashhad, with a population over 1 million. Mashhad's population of more than 1.4 million represented an increase of 110 percent since 1976. Much of its growth was attributed to the large number of Afghan refugees, approximately 450,000, who were living in the city. The historical origins of Mashhad are similar to those of Tehran inasmuch as the city essentially developed after the centuries- old city of Tus, near modern Mashhad, was destroyed by the Mongols. Mashhad has served as the principal commercial center of Khorasan since the nineteenth century, although its major growth has occurred only since the mid-1950s. It also has become an important manufacturing center and has numerous carpet, textile, and food-processing factories.

Iran's other major cities include Esfahan, Tabriz, and Shiraz, all of which had populations of 800,000 or more in 1986. Like Mashhad, these cities have experienced relatively rapid growth since the mid-1950s. All three of these cities are important manufacturing centers, especially Esfahan, where many of Iran's heavy industries are concentrated. Smaller cities (populations of 100,000 to 500,000) such as Ahvaz, Bakhtaran (before the Revolution Kermanshah), Hamadan, Karaj, Kerman, Qazvin, Qom, Rasht, and Urumiyeh (or Urmia, formerly known as Rezaiyeh) also have grown considerably since 1956 (see table 2, Appendix). A total of 30 cities, more than double the number in the 1966 census, had populations exceeding 100,000 in 1986.

Data as of December 1987