Expansion of territorial control. Both Japan and the United States were expanding their territorial control in the early 1900s. Japan had acquired control of Korea in 1895, and it had also acquired control of Taiwan and the Pescadores Islands. The United States had acquired control of the Philippines, Guam, and Puerto Rico in 1898, and it had also acquired control of the Hawaiian Islands in 1898.
Competition for resources. Japan and the United States were both competing for resources in the early 1900s. Both countries were heavily dependent on imported raw materials, and they were both competing for control of the sources of these materials.
Growing militarization. Both Japan and the United States were militarizing in the early 1900s. Japan had built up a powerful navy, and it was also developing a powerful army. The United States had also built up a powerful navy, and it was also developing a powerful army.
Economic growth. Both Japan and the United States were experiencing economic growth in the early 1900s. Japan's economy was growing rapidly, and it was becoming a major economic power. The United States' economy was also growing rapidly, and it was the world's largest economy.
Immigration. Both Japan and the United States were experiencing immigration in the early 1900s. Japan was receiving immigrants from Korea and China, and the United States was receiving immigrants from Europe and Asia.
Urbanization. Both Japan and the United States were experiencing urbanization in the early 1900s. People were moving from rural areas to urban areas in both countries.