The information we found regarding commercial driver's license (CDL) from the Federal Department of Transportation notes that a State determines the license fee, the license renewal cycle, most renewal procedures, and continues to decide the age, medical and other driver qualifications of its intrastate commercial drivers. Interstate drivers must meet the longstanding Federal driver qualifications.

From the licensing information we have seen in most states the intrastate age for obtaining a CDL is already 18. For example in Ohio to get a CDL or CDL instruction permit (CDIP) you are required to be at least 18 years of age and have a valid Ohio State driver's license. The OH BMV adds that employers may impose additional standards and/or higher age requirements.

In Maryland, you also must be 18 to obtain a learner's permit for a CDL Intrastate, 21 years of age for Interstate. In addition you must also have a full driver's license.

If your state currently allows those under 18 to acquire a CDL then it may be possible that they are changing state laws so starting next year the minimum age is 18. To find out for certain you should contact your Department of Motor Vehicles.