You are required by law, if you are a certain age, to wear a helmet on both a motorcycle and all terrain vehicle. For ATV riders that applies to anyone under the age of 16. Riders 16 and over must wear a helmet if they're riding on public property. As for the motorcycle helmet law, it was first enacted in 1968 to include all riders but was amended in July of 1998. It now only requires riders and passengers under the age of 21 wear a helmet. You must also wear a helmet if you only have an instructional permit or if you've only had your license less than a year.