It can depend. One might say that Federal Law is supreme because
it is applicable in all 50 states and all territories of the US.
Whereas, state law is applicable only within the borders of that
particular state. However, while federal and state law sometimes
overlap one another ((i.e.: Bank robbery or interstate autho theft,
etc) federal laws do not, and were not, meant to cover all
eventualities of every possible state ordnance.