The powers of the presidency have expanded throughout the history of the United States to meet the evolving challenges of security and the complexities of administering public services for a growing population. These changes sometimes involve structural transformations of presidential power; otherwise, these expanded powers grow organically over time.
The most prominent reason for increased presidential powers is the increased threat of immediate dangers that require swift response. Constitutionally, Congress holds the authority to declare war and ratify peace treaties with foreign nations. As the nature of security threats has evolved over the centuries, it is now clear that Congress is not capable of responding quickly to urgent security concerns, such as nuclear strikes and terrorist attacks. As a result, the War Powers Resolution grants the president power to order immediate but temporary military action without a Congressional declaration of war.
Another major reason for the expansion of the executive branch of the federal government is administering public services for a growing population. In the early days of American history, the population of the 13 original states was drastically lower than the nation's population in the 21st century. The federal government has grown over time to meet the needs of additional services and entitlements that 21st century citizens expect. Such new demands on the federal government include the Federal Communications Commission, or FCC, and the Social Security Administration. Whenever a new bureau or department opens, it falls within the executive branch of government, which is overseen by the president.