The Federal Motor Carrier Safety Administration (FMCSA) is currently seeking input on their proposed pilot program which would allow younger drivers (between ages 18-21) with experience operating military vehicles to operate commercial motor vehicles in interstate commerce. They estimate that the majority of participants will be Reservists or members of the National Guard.
The proposed 3-year program is designed to examine factors such as accidents, warnings, citations, inspection reports and hours-of-service logs and compare the data from the younger drivers with a group of drivers over 21 to determine how much of a role age plays in terms of safety. The drivers participating in the program would be prohibited from crossing state lines, carrying passengers or transporting hazardous cargo. Additionally, all participating carriers would be required to install electronic logging devices on vehicles operated by the drivers. 
There has been very little in the way of research in this area since the early 1970’s when the Federal Highway Administration first examined the literature and found that drivers under the age of 21 “lack the general maturity, skill and judgment that is necessary in handling commercial motor vehicles.”  In late 2000, interest began to pick back up again as carriers, driver training schools, trade associations and insurance companies backed the Truckload Carriers Association (TCA) in its push for new research on younger drivers.
The outcome of the program could hold implications for the driver shortage which has been attributed to a number of factors, including industry growth and retirement.
The FMCSA is seeking input from the public until September 21, 2016, according to the website: https://www.federalregister.gov/articles/2016
 Miller, Eric, (2016). Pilot Allows Vets Ages 18-21 To Work as Interstate Drivers. Transport Topics.
 Federal Register (2016).A Notice by the Federal Motor Carrier Safety Administration : Commercial Driver’s Licenses; Proposed Pilot Program To Allow Persons Between the Ages of 18 and 21 With Military Driving Experience To Operate Commercial Motor Vehicles in Interstate Commerce