Insurance requirements for commercial vehicles varies depending on the weight of the vehicle, the type of cargo being hauled, or the amount of passengers being transported.
If an 18-wheeler carries 10,001 pounds or more of non-hazardous materials on US interstates, the minimum level of insurance is $750,000. This is just a baseline, and many carriers choose to insure for higher than this, given how extensive and costly injury claims can be.
Trucks weighing less 10,000 pounds but carry radioactive materials must carry $5,000,000 worth of liability insurance. Again, this is due to the extremely high risk of injury should an accident occur. 18-wheelers weighing over 10,001 pounds, carrying hazardous materials require the same amount of insurance. Lastly, private or for-hire commercial trucks weighing 10,001 pounds or more require at least $1,000,000 in insurance.
Passenger vehicles require different insurance coverage, depending on the number of passengers transported. Vehicles carrying 16 passengers or more are required to carry $5,000,000 of insurance. Most will insure for higher than this amount, as a bus carrying 50 people can easily reach that amount in personal injury damages quickly. Vehicles carrying 15 or fewer passengers are required to have $1,500,000 worth of insurance.