Gibbons was the first time they expanded the commerce clause, so far as I know. It unilaterally rewrote “commerce” to mean “navigation,” and if that weren’t bad enough for regulatable navigation to be within one state if the body of water it was on overlapped state lines. This decision is still used today to justify, for instance, EPA rules covering “navigable waterways” consisting of a pond in your backyard.
It explicitly did not recognize any application to intrastate commerce.
The subject to which the power is next applied is to commerce "among the several States." The word "among" means intermingled with. A thing which is among others is intermingled with them. Commerce among the States cannot stop at the external boundary line of each State, but may be introduced into the interior.
It is not intended to say that these words comprehend that commerce which is completely internal, which is carried on between man and man in a State, or between different parts of the same State, and which does not extend to or affect other States. Such a power would be inconvenient, and is certainly unnecessary.
Wickard established the "substantial effects" doctrine that says Congress can regulate anything they "find" to "have a substantial effect on interstate commerce". In Roscoe Filburn's case, he was fined for growing his own wheat, because in doing so he avoided having to buy it, and that would deny someone in another state the opportunity to sell it to him, thus affecting interstate commerce.
Congress explicitly claims this "substantial effect on interstate commerce" in the Clean Air Act, which established the EPA.