That all comes down to company policy and insurance stipulations. I will tell you this - if you're thinking of taking a child OTR, I would strongly recommend not to. A day trip is one thing. Truck stops, customers, et. al are not child-friendly environments, not to mention there are customers who'll only let the driver on their property, and any passengers won't be allowed.
It depends on local legislation
18
18
No age restrictions for a child to ride on a motorcycle in the U.S. Georgia
in WA it is illegal to ride in a truck bed at any age. You must have setbelts
My research has shown there is no age limit. I looked at this when traveling with my newborn in a standard cab pickup truck.
Purchasing insurance for a semi truck requires the same information as that of car insurance. The age of the driver, the drivers driving history, the age and make of the truck and the value of the load.
It is not recommended that anyone ride in the cargo area of any vehicle and in most states it is illegal. In places where there is no law against it, if anyone under 18 is riding in the back, the driver could easily be convicted of endangering a child.
from the age 12 up
if your talking bout age it varies between states
12
12