What is the United States a good example of because of having state and federal taxes/laws?

The United States is a good example of a multi-state nation with powers divided among the state governments and the federal government.

Explanation:

Though the supremacy of the federal government of the United States is considered to be a postulate, the United States Constitution grants numerous powers to the state governments regarding the imposition of taxes and making laws for themselves. These 'powers of the state governments' are protected by the Constitution and hence, cannot be interfered into by either the federal government or the President without any solid reason for intervention.