Final answer:
The increase in presidential power is due to the growth of the United States as a world power and the national government. The president's role as leader, diplomat-in-chief, and commander-in-chief has become more significant on the international stage. The rise of electronic mass media has allowed presidents to communicate directly with the public, further strengthening their power.
Step-by-step explanation:
The increase in presidential power can be attributed to the growth of the United States as a world power and the growth of the national government. As the nation has grown and developed, people have looked to the federal government more often for solutions to the increasing complexity and size of the domestic economy. Additionally, the rising profile of the United States on the international stage has made the president a more important figure as leader, diplomat-in-chief, and commander-in-chief. With the rise of electronic mass media, the president can now communicate directly with the public, further enhancing their power.