According to thomas jefferson, any powers not expressly delegated to the federal government by the constitution are reserved for the

People [He believed the power should be reserved for people in the United States, specifically those white men who owned land and could vote but hey whats new]

States. He believed if a power was not specifically given to the federal government, state government had the authority. This was to make sure state and federal laws did not contradict one another, and also to not make the federal government too powerful; only local and states governments would make laws that would benefit and be specific to the people living there.