Since the 1930s and the entry of the United States into the Red Line Agreement in 1928, the issue of expanding American influence in the Persian Gulf and later in Iran has been raised. Because he wanted to use his influence in the Persian Gulf to dominate the huge energy wealth of this region. Therefore, the goals of this research in the first stage are to know and analyze the American policies in the Persian Gulf, then to investigate and know the ways of American influence in Iran relying on the Persian Gulf, and the last goal is to know the changes and developments that the United States made in the Persian Gulf and Iran. . According to these goals, the main issue of this research is to explain the role of the Persian Gulf in the formation of influence in Iran by America in the years 1928 to 1979. Two main and secondary questions are answered in this research. What role did the Persian Gulf play in expanding American influence in Iran? As the main question, how did the global conditions and developments and other countries affect the American influence in the Persian Gulf and Iran? It is a sub-question of this research. To answer these questions, Persian and Latin articles, books and documents have been used and after examining and analyzing them, they have been used in the text in a descriptive-analytical way. Through research in the years 1928 to 1979, several findings were obtained that show that the United States, from the Red Line Agreement in 1928 onwards, with various investments, oil contracts, securing the Persian Gulf region, creating influence in governments, individuals and elites , lobbying and even militarism in the Persian Gulf would consolidate its influence in this region and pursue its own goals by influencing Iran.