The federal government performs a number of functions, including maintaining national security, establishing trade agreements with foreign nations, initiating national infrastructure projects and determining the value of currency.The federal government has only those powers specifically granted to it in the U.S. Constitution. However, as time has passed, lawmakers have interpreted the enumerated powers in ways that give the federal government – and especially the executive branch – increasingly greater power.
Cornell University's Legal Information Institute states that the federal government has jurisdiction over issues that affect the entire country. The most basic is the issue of national defense. The federal government has the power to raise and train a military. Congress has the authority to declare war, and the President is the commander in chief of the armed forces.
Another vital function of the federal government is authority over the printing of money and also determination of its value.
The scope of the federal government has expanded immensely. It now has many regulatory roles and social welfare programs. Federal agencies regulate food hygiene, the environmental consequences of business operations, the business practices of banks and the educational performances of the nation's schools. The federal government also provides financial aid to college students, government housing to the homeless, stipends to the unemployed and food stamps to the poor.
The federal government is also responsible for running the United States Post Office.