As far as medical use, marijuana is proven to help with MS, chemo treatment, HIV/AIDS patients, arthritis, sleep disorders and many, many more. Marijuana is also safer than many current prescription medications.
When it comes to recreational use marijuana is much safer than legal drugs such as tobacco and alcohol. While thousands a year die from tobacco and alcohol related complications, there has never been an overdose from marijuana.
Legalization would also be hugely beneficial to the national economy in the way of creating thousands of jobs and create millions of dollars in tax revenue annually as well as save more millions by not spending tax payer money on the prosecution and jailing of countless Americans for something a growing majority of citizens believe shouldn't be a crime