ABSTRACT. In this paper I analyse how the economic agglomeration of a port is affected by the integration of companies composing it into international supply chains, studying the specific case of container terminals from Constanta Port. To notice the effects that supply chains have on the economies of agglomeration Iobserve internal and external economies from the perspectives of scale, scope and complexity. Afterwards, to emphasize the distinction between supply chains and agglomeration economies I engage in a comparative study between a global and a local terminal operator, both active on Constanta Port container handling marketKeywords: economies, supply chain, container terminal, Constanta PortJEL Classification : R11, R12, L91, L14, L20IntroductionFor centuries, ports have formed locations for agglomeration of economic activity. The obvious reason for this is the existence of a set of conditions favourable for the outbreak and development of specialized activities related to the handling of goods and passengers. These conditions are composed of geographical location and the provision of specialized infrastructure. Therefore, shared inputs in infrastructure become foundations for shared inputs in economic activity, thus facilitating the development of industrial concentrations with their derived agglomeration economies.In terms of the deterritorialization of production activities (Scholte, 2000) from the last 20 years, against the context of unprecedented growth in the flows of goods, services and knowledge and the mobility of persons (Zaharia, 2004), a paradigm shiftoccurred in the functions that ports, seen as clusters of specialized economic activities, fulfil. Thus, they began to be perceived as integrated elements in value-driven chain systems (Robinson, 2002). In the role of key elements of international supply networks, companies located in ports become virtually dependent on the activity of the networks they belong to. In the case of port economic agglomerations, there is a shiftof analysis from the firms in the system to the system of firms.Although there is a growing number of papers recognizing the important role that ports play on international supply chains (Slack and Fremont, 2005, Carbone and De Martino, 2003, Bichou and Gray, 2004, 2005, Robinson, 2006, Panayides and Song, 2009) there have been limited empirical investigations on how supply chains affect economies of agglomeration located in ports. In fact, the association between the theory of economies of agglomeration and that of supply chains is not a common one. This is mainly because of the contrasting nature of the two theories, one stressing the importance of geographical proximity, and the other one the global network. This paper provides a mean to bring together the two divergent theories by reuniting them on the common ground represented by a seaport.Understanding how agglomerations, in all their perspectives of scale, scope and complexity are affected by the integration in the supply chains, in the specific context of a particular port (Constanta Port) is the goal of this paper. For accomplishing this objective, the research will focus on revealing the effects that integration in international supply chains has had on the economies of agglomeration occurred in container terminal operations, one of the most dynamic segments of port activity, that greatly impacts the whole of port economic agglomeration. The analysis will not stop only to the container operations segment, but will also employ specific empirical evidence, in order to underline the discrepancies between a segment of the port market that is integrated in supply chains and the rest.The article is organized as follows. In the next section I review the literature specific to agglomeration economies in order to define the main aspects of theoretical issues. In the second section I analyse the main features of a port economic agglomeration. …