Constantinople and Angora change their names to Istanbul and Ankara.

The renaming was not ceremonial. On March 28, 1930, the Turkish government informed international postal and telegraph services that Constantinople was now Istanbul and Angora was now Ankara, threatening to return any mail addressed to the old names. The decree formalized what had been common Turkish usage for centuries but forced the rest of the world to acknowledge that the Ottoman Empire was truly gone and a modern, secular nation-state had replaced it. Mustafa Kemal Ataturk had been dismantling the Ottoman past since founding the Turkish Republic in 1923. He abolished the sultanate, then the caliphate. He replaced Arabic script with Latin letters, banned the fez, adopted the Gregorian calendar, and gave women the right to vote. Renaming the cities was part of this systematic effort to create a Turkish national identity distinct from the multicultural, multilingual Ottoman world. "Istanbul" derived from the medieval Greek phrase "eis tin polin," meaning "to the city," a colloquial name that Turks had used alongside "Konstantiniyye" for centuries. "Ankara" replaced the Western form "Angora," which Europeans associated with the city's famous goat wool. Ataturk had deliberately moved the capital from cosmopolitan Constantinople to the smaller Anatolian city to signal that the new Turkey would be rooted in its Asian heartland rather than oriented toward Europe. The international community adapted slowly. The New York Times continued using "Constantinople" in headlines into the mid-1930s. Maps and atlases took years to update. But the name change stuck, and Istanbul's identity gradually shifted from an imperial capital that had served Romans, Byzantines, and Ottomans into a modern metropolis that anchored Turkey's 20th-century transformation from caliphate to secular republic.