The Constitution grants certain powers only to the federal government. These powers are called the enumerated powers. Some powers are granted only to the state governments. These are called the reserved powers. Some powers belong to both the state and the federal government. These are called concurrent powers.

There are several examples of enumerated powers. Only the federal government can make treaties with other countries. If the United States goes to war, the federal government will make the peace treaty. Additionally, the federal government would decide if we were going to go to war with another country. During the days when the Articles of Confederation was our plan of government, both the state and federal government made money. This caused many problems. Today, only the federal government can make money. Finally, the federal government regulates both interstate and foreign trade.

The federal government has some other powers that state governments also have. For example, the federal government can levy taxes, borrow money, build roads, and establish courts. The state governments also have these powers.

First, another important power reserved to the federal government is to create laws governing patents and copyrights. States may not grant copyrights or patents for any invention or work of art. 

Second, the Tenth Amendment provides that powers not granted to the federal government nor prohibited to the states belong to the states belong to the states.  So, the founding fathers contemplated that other kinds of powers could easily have been left out and the Constitution does not allow the federal government to assume those powers.  They must go to the states.  These include education and laws governing marriage and divorce. 

Finally, I think it is worthy of mentioning the reasoning behind which powers are reserved to the federal government and which do not go to the states.  In each and every instance, allowing states to have these powers would have led to us not being a true nation at all and would have had dire consequences from a purely practical point of view. Imagine what would happen, for example, if each state had its own postal system. You would need a stamp to get a letter from California to Arizona, another stamp to get it to New Mexico, and so on.  For a letter to get from California to New York would have been burdensome at best.  The same is true of a monetary system. Who wants to go from Pennsylvania to Ohio and have to go exchange to the local currency?  In terms of treaties or warfare, it would not work very well for Maryland to have a treaty with Spain while Virginia declared war upon Spain.  The founding fathers really thought this through, contemplating how this system would work out practically and how some kinds of powers must be national in order to have a true nation.  It never ceases to amaze me how intelligently all of this was done.

Some of the powers delegated to the federal government by the United States Constitution include the following:

• the power to coin money
• regulate commerce with foreign nations
• regulate interstate commerce
• establish post offices
• punish crimes committed on the high seas
• establish import duties and tariffs
• fix standard weights and measures
• raise and maintain the armed forces
• declare war and peace
• enter into treaties with foreign powers
• call out the militia to deal with insurrections

The federal government has many other powers that it exercises jointly, or concurrently, with the states. These include the power to tax, create and maintain courts, and many others.