Iran is subdivided into thirty one provinces (Persian: استان‎‎ Ostān, plural استان*ها Ostānhā), each governed from a local center, usually the largest local city, which is called the capital (Persian: Markaz) of that province. The provincial authority is headed by a Governor-General[1] (Persian: Ostāndār), who is appointed by the Minister of the Interior subject to approval of the cabinet.
According to the Encyclopedia Britannica,[2] in 1911 there were thirty-five administrative divisions in Persia, as follows:

Provinces
Khuzestan and Bakhtiari
Astarabad and Gurgan
Azerbaijan
Fars
Gerrus
Gilan and Talish
Hamada[n]
Irak, Gulpaigan, Khunsar, [Kezzaz, Ferakan, and Tusirkhan]
Isfahan
Kashan
Kazvin
Kerman and Baluchistan
Kermanshah
Kamseh
Khar
Khorasan
Kum
Kurdistan
Luristan and Burujird
Mazandaran
Nehavend, Malayir and Kamereh
Savah
Samnan and Damghan
Shahrud and Bostam
Teheran
Zerend and Bagdadi Shahsevens
Dependencies
Asadabad
Demavend
Firuzkuh
Josehekan
Kangaver
Natanz
[]
Tarom Ulia
Kharakan
Until 1950, Iran was divided into twelve provinces: Ardalan, Azerbaijan, Baluchestan, Fars, Gilan, Araq-e Ajam, Khorasan, Khuzestan, Kerman, Larestan, Lorestan, and Mazandaran.[3]

In 1950, Iran was reorganized to form ten numbered provinces with subordinate governorates: Gilan; Mazandaran; East Azerbaijan; West Azerbaijan; Kermanshah; Khuzestan; Fars; Kerman; Khorasan; Isfahan.[3]

From 1960 to 1981 the governorates were raised to provincial status one by one. Since then several new provinces have been created, most recently in 2004 when the province of Khorasan was split into three new provinces[4] as well as splitting of the new Alborz Province from Teheran province in 2010.