Answer:
Federalism is a system of government in which the same territory is controlled by two levels of government. Both the national government and the smaller political subdivisions have the power to make laws and both have a certain level of autonomy from each other.
Step-by-step explanation:
Dual federalism describes the nature of federalism for the first 150 years of the American republic, roughly 1789 through World War II.
Federalism is needed within the USA to provide consistency between all the states and provinces of a country. If you have inconsistent rules across a nation, you will have many situations where different people act in an identical manner, but act illegally in one state.
In a federal system, power is shared by the national and state governments. The Constitution designates certain powers to be the domain of a central government, and others are specifically reserved to the state governments.