A person must be at least ____ to drive a CMV across state lines. Question A person must be at least ____ to drive a CMV across state lines. Answers 18 years old 21 years old 25 years old Explanation A driver must be at least 21 years old to operate a CMV in interstate commerce. Drivers may be 18 years old to drive a CMV only within the state of Michigan. This questions appears in the following tests: Michigan Class A Knowledge Test