After nationalizing various companies and combining them in 1939 with law 3645, the “Istanbul Electric Tram and Tunnel General Directorate” reached the status it has today.

[8] Today, the IETT only handles public transportation including buses, trams and tunnels as well as the administration, management and supervision of Istanbul Ulaşım A.Ş.

Urban transportation in Istanbul began with the founding of the Dersaadet Tram Company and the decision to construct the Tünel.

In 1912, during the Balkan Wars, all horses were sent to the front line, and therefore all horse-operated tram services were suspended for a year.

On October 29, 1933, all 320 trams and 4 buses were ordered directly by Mustafa Kemal Atatürk to fully operate, as part of the 10th year anniversary celebrations of the founding of the Republic.

After the materials were taken from customs, they were immediately assembled, but because the factory in the United States stopped production, only nine White Motor Company buses could enter service.

[17] By the end of that same year, 25 Scania-Vabis brand motorbuses were imported from Sweden and allocated to the IETT.

[20] A short while after, 12 Twin Coach, 2 Chevrolet and 1 Fargo brand buses were bought to make a fleet of 15 with the help of the municipality.

[16] Bus purchased continued in 1979-1980 with Mercedes-Benz, Magirus and Ikarus brand buses and with MAN in 1983-1984.

[23] The IETT also has 3,075 buses under the Private Public Bus (Turkish: Özel Halk Otobüs) brand.

Under the law passed on September 17, 2020, by the Metropolitan Municipality Council, buses under Istanbul Ulaşım A.Ş.

Under the modernization movements during the Second Constitutional Era, the right to distribute electricity was given to the Ganz Corporation after careful investigation.

[28] The production and distribution business, which was carried out by private companies with foreign capital first in Yedikule until 1878 and later in Kadıköy in 1891, was transferred to IETT in 1945 with the law numbered 4762, after having changed hands a few times.

The company, which also produced and sold coke and employed around a thousand people, had an average daily capacity of 300 thousand cubic meters until it was liquidated in June 1993 due to the introduction of natural gas into daily life and outdated technology.