Final answer:
The main conflict between 1900-1950 was the Cold War between the United States and the Soviet Union. Proxy wars and a global divide between capitalism and communism occurred as a result.
Step-by-step explanation:
The main conflict between 1900-1950 was the Cold War between the United States and the Soviet Union. These two superpowers competed for political control and natural resources in newly formed countries emerging from colonial rule. The Cold War resulted in proxy wars, such as the Korean War and the Vietnam War, and created a global divide between capitalist and communist ideologies.