The teenth Amendment.​

The Tenth Amendment's simple language—“The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people”—emphasizes that the inclusion of a bill of rights does not change the fundamental character of the national government.

Explanation:

do you have a list of sources to choose from?

the constitution gives congress the power to regulate commerce "among" the several states.