Riding ATV’s on public roads (roads paid for and maintained by township, county, state, or national taxes) is illegal. Vehicles on public roads need to be registered, and insured in just about every state. You are simply taking your chances about whether or not you will get caught in the act.
You might want to check out the fines and court costs and whether or not this is an offense that puts points on your driver’s license. In rural PA folks ride ATV’s on roads all the time. Most commonly on dirt roads.
KIds riding ATV’s recklessly were such a problem in my community (a private development) that ATV’s are banned. Our private security guy follows the offenders home and issues several citations which run into significant fines.
Some ATV’s use high powered motor cycle and snowmobile motors and are capable of speeds in excess of 100mph. Others are “mule” type work vehicles that don’t go nearly as fast. A high speed ATV in the hands of a poor rider, or a drunk one, can do a lot of damage. We see several fatalities every year with ATV accidents.
It is up to you to make the call on what to do in your area. Just be sure of the risks before you make the decision. You are basically doing the same thing as a motorcycle rider running an unregistered and uninsured vehicle on public roads.