When and how does a place become a border, or a frontier? The answers to such a question depend on the historical period. Borders and frontiers were much more fluid and permeable before the formation of the modern state and especially a certain type of it, the modern nation state. Extraterritoriality, complexity and fluidity that were once prominent features of pre-modern states, and of borders, became menaces to be cured for nation states. The relationship between states and their societies had to be redefined. The history of the emergence of nation states out of the Ottoman imperial framework provides us with cases of particularly violent and rapid transitions from ‘heartlands’ to ‘borderlands’. The Ottoman county of Foçateyn used to be located at the ‘heartland’ of the Ottoman Empire, on the western Anatolian seaboard. After the Balkan Wars (1912-1913), it turned into a ‘borderland’. The costs of this transition were drastic. Eski Foça, the center of the Ottoman county of Foçateyn, was a boomtown located on the shores of western Anatolia. Muslims—Kurdish, Turkish or others—had long been the residents of the county along with non-Muslims such as Greeks, Armenians and Jews. This cosmopolitan outlook reached its peak towards the end of the 19th century when the town and the county were incorporated with the world economy. Growth attracted migration and the demography of the county changed in favor of Ottoman Greeks whose numbers comprised the majority of the population on the eve of the Balkan Wars. This paper will analyze the transformation of Foçateyn from a county possessed of a cosmopolitan outlook and incorporated economy into one whose population became homogeneous and whose economy became dominated by the state. It will argue that a clear correlation existed between the transformation of the county of Foçateyn into a borderland, on the one hand, and the radical demographic and economic transition it experienced, on the other.