Local governments, as the closest units to the public in their service areas, are the institutions responsible for fulfilling the unlimited wishes of their compatriots. It is demanded that the service provided to the citizens be flawless, but the municipalities cannot keep up with all areas, thus reducing efficiency. Considering that competition and cooperation have become important for local government units; local government unions have taken their place among the important institutions in order to increase both the quality and diversity of the service offered to the citizens and the efficiency. While preparing this study, literature review and document review method from qualitative research methods were used. Local government unions are one of the areas where solidarity between municipalities takes place. Local government unions established with the understanding that unity is stronger; It mediates the emergence of knowledge and experience opportunities among its members, and provides consultancy to municipalities at the point of producing solutions to common problems encountered with a culture of solidarity. It also helps municipalities to direct them to the right partner in sister city relations and thus to develop sustainable sister city relations. As a result of globalization, as a reflection of the interaction between countries, international relations have started to develop between cities and the areas of cooperation that can be made in this sense have also developed. Local partnerships and collaborations established between local government units between countries have added new meanings to the international dimension of municipalities. Motivating reasons such as the effort to become a global city, their attempts to search for partners in resource use and finding, and their desire to take part in global competition have led municipalities to cooperate. The most common of these collaborations are local government unions and sister city  relations, which have a long history but have increased in importance in the last fifty years. Cities have also entered the process of change due to reasons such as diversification of needs, globalization, and the transition to a consumer society, and world cities have begun to be transformed around global capitalist relations. However, politics has been moved to an area above the nation-states, so the need for regional and international organizations has increased. Most of the interactions that were experienced between nation states in the past are now experienced between cities. Changes are being experienced in areas such as the forms of delivery of city services, city management systems, spatial structures of cities, urban identities and consumption habits. In this process, even the urban space has been commodified, and a race has begun between cities to attract international capital to cities. At this point, cooperation has become inevitable. Since local governments have a say in cities on a regional basis, the cooperation of local governments in the national and international arena gains even more importance in this race.