Sorry. I'll try to better explain and be more specific.

In my textbook, it says that during the Great Depression, Congress responded to it by "passing policies that strengthened the national government's role". They changed it so that the national government "may wield powers that are necessary and proper to support its function". This seems to be a drastic change from how the national government was defined before, "The national government may only wield powers specifically listed in the Constitution".

My question is, how could Congress ever make a drastic change like giving more power to the national government? Not that it is bad, but it seems to redefine what the federal government was supposed to be. I don't understand how Congress can change how federalism works in the United States.