The Commerce Power:

The Congress shall have Power To... 

 To regulate Commerce with foreign Nations,
 and among the several States,
 and with the Indian Tribes;

[Art. I, Section 8]

What's Within the Commerce Power of Congress?

"First, Congress can regulate the channels of interstate commerce.

Second, Congress has authority to regulate and protect the instrumentalities of interstate commerce,
and persons or things in interstate commerce.

Third, Congress has the power to regulate activities that substantially affect interstate commerce."

(Gonzales v Raich 2005).