TCDD took over the Chemin de fer d'Anatolie-Baghdad, a holding company formed in 1924 by Turkey to take over some rail lines in Turkey, on 1 June 1927 and had control over the tracks of the former Anatolian Railway (CFOA) and the Transcaucasus Railway line in Turkish borders.

TCDD continued to build lines, reaching Zonguldak, Erzurum, Erzincan, Diyarbakır and Elazığ in the following years.

Intercity, regional, suburban, freight and most industrial lines are owned and operated by the State Railways.

In the railway's first year 52% of passenger travel in Turkey was by rail, despite the system lacking connections to many parts of the country.

[9] Today, the passenger ratio is slowly increasing with the opening of high-speed rail lines in Turkey.

There had been previously tried but failed accelerated train projects, i.e. higher speed rail without the necessary upgrades on the railroad tracks, causing a number of accidents and ending up with losses incurred by TCDD in early 2000s.

In total, these lines connect 8 provincial capitals out of 81 Provinces in Turkey, namely Adapazarı (via Arifli), Ankara, Bilecik, Eskişehir, Istanbul, İzmit, Karaman and Konya.

[citation needed] High-speed rail in Turkey is still developing, with new lines currently under construction or in the planning phase.

By 2023, the Ministry of Transport and Infrastructure expects Turkey's high-speed rail system to increase to 10,000 kilometers.

Express service is between major cities and are fast, comfortable and equipped with modern air-conditioned TVS2000 railcars and only stop at important stations.

[citation needed] The TVS2000 railcars used on mainline service are the most comfortable cars in TCDD's entire fleet.

The first commuter rail service in Turkey was the Istanbul-Halkalı Line on the European side of Istanbul, operating from Sirkeci Terminal to Halkalı in 1955.

[24] Approximately 50% of freight moved is minerals or ores, with construction materials increasing to ≈10% in 2000 from less than 5% in 1980, food/agricultural products, chemicals/petroleum, and metal sectors each account for between 5 and 10%.

Two steel companies, Erdemir and Kardemir, top 2 customers of TCDD, had transported 4.5 million tons in 2012, mainly iron ore and coal.

[30] TCDD is planning to increase its transit traffic (11000 to in 2011) by constructing "iron silk road" to connect Europe to Asia.

A similar trend was observed in the percentage of passenger transport performed by rail – dropping from a share of greater than 40% in 1950 to ≈25% in 1960; less than 10% in 1970; ≈5% by 1980; and reaching an all-time low of 2% by 2000.

[47] In addition to the problems caused by the lack of investment from 1950 onwards, the TCDD organisation has been characterised as suffering from the common problems associated with state-owned enterprises; i.e. emphasis on production rather than customer needs; subject to government reliance and interference; and an inward-looking corporate culture.

[47] As of 2008, the amount of freight transported was the highest ever (18.343 million tonne-kilometers); though actual growth was small over the previous 10 years, and passenger figures had risen slightly overall over the past decade.

[citation needed] Railways powered by electricity in Turkey comprised less than half of the network in 2020, but the aim is for over three-quarters by 2023.

[52] Along with these several Turkish cities operate rapid transit and tram system electrified with either overhead wire or third rail.

The State Railway then turned to electrify the entire İstanbul-Ankara main line, to try to save its diminishing reputation.

The major ore route between Divriği and İskenderun was electrified in 1994 to make it easier for heavy trains to go up steep gradients.

[citation needed] The United Kingdom through Export Finance, a credit agency gave a Turkish multinational a €781m loan to finish the High speed rail.

[55] Rönesans Holding, the Dutch Turkish company in charge of the project is required by the UK to be supplied by British suppliers.

The line from Arifiye outside Adapazarı to Eskişehir were further electrified in 1989 and in 1993 to Sincan, allowing electric train passages from Istanbul to Ankara.

[58] TCDD is constructing 18 logistic centers to be completed till 2023 to increase the portion of railway in freight transportation.

[30] These centers (also called as freight villages) will have railway connected container yards, cranes, warehouses, customs service and other facilities.

These 18 logistic centers are: Halkali, Samsun-Gelemen, Usak (completed) Kosekoy-Izmit, Hasanbey-Eskisehir, Kaklik-Denizli, Bogazkopru-Kayseri (partially completed) Yesilbayır-Istanbul, Gökköy-Balikesir, Bozüyük-Bilecik, Kayacık-Konya, Yenice-Mersin, Sivas, Türkoğlu-Kahramanmaraş, Kars, Palandöken-Erzurum, Mardin (under construction) Marşandiz Yard is in Ankara.

Sultan Alparslan and Idris-i Bitlisi are the names of the ferries that operate on the route and are also fully owned by TCDD.

[61] Other train ferries: The Turkish State Railways currently has many network extension and modernization projects planned.