Hello, I am over 21 years old, French license, Is it mandatory to have international driving license for a 1 month trip to the USA? I will be in the state of California. In advance, thank you for your answer.

The international drivi g license might be useful if you get stopped by the police. California should be OK though.

No you don't need international license but you will be charged underage fees

I Am italian, I have the international one but NOBODY ASKED that one. Everyone wanted from me the italian one, hertz As Well.

Thank you for your answer!