You have to be 18 years old and have a driver's license for at least a year. From 18 to 20 years old you can only drive commercially intrastate, or within the state you hold your commercial license. Once you are 21 you can drive interstate, in other words cross state lines in a commercial vehicle. Right now there is a pilot program to allow an 18-20 year old drive across state lines.
While I was taking the training course there was another person getting her class-A CDL that was 19. But I do believe you still need to be 21 to drive semi trucks.
I believe its 21. Call their head office to make sure. There is a government program starting to see if people at the age of 18 can drive truck safely though.
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