Answer:
The principle of federalism establishes that the government will be divided into different territorial sub-entities, in order to the better administration of the power of the state. Thus, the United States has a central federal government, and 50 state governments, which exercise limited power to their territory and in turn are divided into counties.
Thus, within the same territory, there may be three levels of power: the local power exercised by a mayor; the state power exercised by the state governor; and the federal power exercised by the President of the United States. This makes citizens better represented, since their local, regional and national issues are always addressed differently.