The 2018 Federal Farm Bill removed hemp from the controlled substance act and made hemp a legal agricultural commodity in the United States. However, each state can have its own regulations over hemp that do not trump the federal rulings. Therefore, in some states,hemp production is still illegal. Vote Hemp is an industrial hemp advocacy group that does a great job at keeping up to date to legislation regarding industrial hemp.
If you want to verify where cultivation of industrial hemp is legal in your state, click "Details Here" under your respective state. To leave legacyhemp.com and go to Vote Hemp's corresponding webpage.