Final answer:
World War I, The Great Depression, The Cold War, and the 9/11 attacks are events that have contributed to greater presidential power.
Step-by-step explanation:
Since the start of the 20th century, several events have contributed to greater presidential power in the United States. These events include:
- World War I: The war led to a greater focus on international affairs, which increased the role of the president as the nation's leader and diplomat-in-chief.
- The Great Depression: President Franklin D. Roosevelt's response to the economic crisis expanded presidential power by introducing new economic policies and programs.
- The Cold War: The United States' rivalry with the Soviet Union during the Cold War gave the president increased authority in matters of national security and foreign policy.
- 9/11 attacks: The terrorist attacks on September 11, 2001, led to the expansion of presidential powers in the areas of national security and counterterrorism.