Overseas military bases, a very important strategic fulcrum, are the forefront of a country's military operations and safeguarding national interests outside the country. In different periods, the contraction and expansion of overseas military bases can reflect the country's space strategy and growth laws. This paper analyzes the evolution of the space-time pattern of military bases outside the United States from the end of the 19th century to the present, summarizes the existing organizational models, and reveals the internal dynamics of the evolution of overseas bases. The study finds that the evolution of military bases outside the United States has gone through five major stages. The first stage is the slow westward extension of the Pacific Ocean, the second stage is to accelerate the eastward entry into the Atlantic Ocean, the third stage is the east-west expansion in both directions, the fourth stage is an extensive global layout, and the fifth stage is a comprehensive reduction and layout adjustment. In the process, the spatial location of military bases outside the United States has formed three main types,including island type, continental coastal type and inland type. The overseas military bases of the United States have realized the coverage of key strategic channels in the world, and the military radiation to major countries and important sea areas through the coordination of base groups and the configuration of forces and arms. Finally, based on the military, political, and economic dimensions, this paper reveals the dynamic mechanism of the evolution of the military base structure outside the United States from the aspects of national homeland security, geostrategic evolution, diplomatic relations with major countries, and energy and transportation.
