Towards the end of the 19th century, the Pan-American project implied a series of political, economic, and cultural strategies that increased the influence of the United States in Latin America. In this context, the countries of the Southern Cone began accepting arbitration by American presidents or delegates in territorial border conflicts. The article analyzes the participation of the United States in the conflict between Argentina and Chile over the Puna de Atacama (1899). This approach aims at identifying the contributions of the United Sates in the selection of criteria to negotiate the border, in the first place, and, secondly, to explore the connections between said arbitration and Pan- Americanism in the region. [ABSTRACT FROM AUTHOR]