Federalism can be defined as a form of government in which powers are divided between two levels of government of equal status. Modern federalism is a system based upon democratic rules and institutions in which the power to govern is shared between national and state governments. In the US, the Federal government has the power to make laws about certain specified matters which are considered too difficult for the States to manage, so that the States retain all other areas of responsibility. It is common that during the historical evolution of a federation there is a gradual movement of power from the component states to the centre, as the federal government acquires additional powers, sometimes to deal with unforeseen circumstances. The acquisition of new powers by a federal government may occur through formal constitutional amendment or simply through a broadening of the interpretation of a government's existing constitutional powers given by the courts.
That is not how Federalism works
Federalism can be defined as a form of government in which powers are divided between two levels of government of equal status. Modern federalism is a system based upon democratic rules and institutions in which the power to govern is shared between national and state governments. In the US, the Federal government has the power to make laws about certain specified matters which are considered too difficult for the States to manage, so that the States retain all other areas of responsibility. It is common that during the historical evolution of a federation there is a gradual movement of power from the component states to the centre, as the federal government acquires additional powers, sometimes to deal with unforeseen circumstances. The acquisition of new powers by a federal government may occur through formal constitutional amendment or simply through a broadening of the interpretation of a government's existing constitutional powers given by the courts.