• "Federalism" is the process by which two or more governments share powers over
  the same geographic area

• In the United States, the Constitution grants certain powers to both the U.S. government and the state
  governments.

• Things the states cannot do are listed in Article I, Section 9. Among these,
  states are forbidden from coining money, entering into treaties, charging duties
  on imports and exports and declaring war.

• Under the 10th Amendment, powers not specifically listed in the Constitution,
  like requiring drivers licenses and collecting property taxes, are among the
  many powers "reserved" to the states.

        

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