The Constitution enumerates certain powers which are reserved to the federal goverment and other powers which are delegated to the state.
Those powers which are not explicitly related in the document to any of the goverment levels will automatically be reserved to and exercised by the supreme federal goverment.
It was known that there was an economic boom taking place just after the second world war. It could be due to effective economic policies implemented by various governments. Such policies include the reduction of the tax rates, and economies were regulated so as to avoid excessive spending.