Marijuana is one of the most interesting ways that state law conflicts with federal law, since it remains illegal at the federal level but the federal government chooses not to prosecute it. States of Democracy divides states into four groups based on their marijuana laws:

• Bad (0): marijuana is illegal
• Below Average (1): marijuana is legal for medical purposes
• Good (2): marijuana is legal for medical purposes, as well as generally decriminalized
• Very Good (3): marijuana is legal for recreational use

Data Source

Legality of cannabis by U.S. jurisdiction - Wikipedia