What 391.11B1 means in plain language
FMCSR 391.11B1 prohibits operating a commercial motor vehicle in interstate commerce if you are under 21 years of age. This is a federal driver fitness requirement, not a state licensing rule—it applies to any CMV crossing state lines, regardless of what your home state allows.
Interstate commerce means hauling cargo or passengers that cross state boundaries. Local delivery routes that stay within one state may have different age rules under state law, but the moment your trip crosses a state line, you must be at least 21. This applies to tractor-trailers, straight trucks, and any vehicle requiring a CDL when operated in interstate business.
If you were cited at roadside for this violation, the inspector determined you were driving a CMV in interstate service while under 21. The citation is logged in your safety record and becomes visible to future employers, insurance companies, and the FMCSA.
What our enforcement data actually shows
Across our 13 million inspection records, we have documented 263 all-time citations for 391.11B1, with 91 citations in the last 12 months and 17 in the last 90 days. This ranks 391.11B1 at #1129 of 3,036 FMCSR codes by citation volume—not the most common violation, but consistent enough that inspectors actively check driver age.
The enforcement outcome is severe: our data shows a 94.7% out-of-service rate for this code. That means in 249 out of 263 all-time inspections where 391.11B1 was cited, the driver was placed out of service on the spot. Compare this to the all-FMCSR average out-of-service rate of 31.4%—this violation triggers immediate removal from service at a rate roughly three times higher than the average violation.
When you are placed out of service for this citation, you cannot legally operate a CMV again until the condition is corrected (in this case, reaching age 21) or the citation is contested successfully.
Who gets cited most
Our inspection data from the last 180 days shows the highest concentration of 391.11B1 citations in New Mexico, Iowa, and North Carolina.
New Mexico recorded 13 citations with a 100.0% out-of-service rate. Iowa had 12 citations, also at 100.0% out-of-service. North Carolina reported 5 citations with 100.0% out-of-service. Texas had 5 citations but a lower 60.0% out-of-service rate, suggesting some citations may have been dismissed or downgraded upon review. Illinois recorded 3 citations at 100.0% out-of-service.
The consistency of 100% out-of-service rates in the leading states reflects the objective nature of the violation—if you are under 21 and operating in interstate commerce, there is no gray area.
Our all-time carrier data shows no single carrier with a dominant pattern. The highest frequency belongs to a group of carriers with 2 citations each, including LAND OF LIGHT TRANSPORT LLC, GATERY TRANSPORT LLC, and BUXTON UTILITIES LLC. This distribution suggests the violation is scattered across the industry rather than concentrated in particular fleets, though it underscores that all carriers risk occasional underage driver citations if hiring or deployment controls are weak.
How severe is this compared to similar codes
With 263 all-time citations, 391.11B1 is far less frequently cited than other driver fitness violations in the same category. For comparison:
383.23(a)(2) (CDL – wrong class) has generated 50,385 all-time citations with a 98.4% out-of-service rate. That code is cited roughly 191 times more often than 391.11B1, but the out-of-service rates are similar (94.7% vs. 98.4%), showing that both are treated as hard stops by inspectors.
391.41APC (medical certificate missing/invalid) has 49,539 all-time citations at a 97.1% out-of-service rate—again, much higher volume but comparable severity.
391.41(a) (physical qualification general) stands out as a peer code with much higher citation volume (42,270) but a dramatically lower 16.2% out-of-service rate. That contrast shows that age violations are enforced more stringently than other physical qualification issues, which may be corrected or waived more readily.
The near-universal out-of-service placement for 391.11B1 reflects FMCSA policy: this is treated as a disqualifying violation with little discretion at roadside.
How to avoid it
The solution is straightforward but non-negotiable: you must be at least 21 years old before operating a CMV in interstate commerce.
For drivers approaching 21, understand your legal status:
- Do not accept interstate driving assignments before you turn 21, even if your employer or a broker offers them. The citation and out-of-service placement will follow regardless of whether the shipper or carrier pressured you to take the load.
- Confirm your birthdate and driver's license are current before every trip. Inspectors verify age using your CDL; an expired license can create additional violations even if your age is acceptable.
- If you are under 21, restrict yourself to intrastate or local routes where state law may permit younger drivers. Know your home state's rules and stay within those limits.
- Alert your dispatcher or safety manager immediately if you have upcoming travel near a state border. Some routes that appear "intrastate" may cross state lines without the driver realizing it.
For fleet managers: Our co-occurring violation data from the last 90 days shows that 391.11B1 inspections sometimes coincide with other mechanical and equipment issues (e.g., 393.95A fire extinguisher defects, 393.75A3 tire problems, 393.43D brake valve issues). This suggests underage drivers may be operating older or inadequately maintained vehicles. Pair age verification with robust pre-trip and post-trip vehicle inspections to catch both problems.
Monitoring your driver roster for upcoming 21st birthdays and scheduling age-restricted drivers for intrastate work until that milestone is a simple control that eliminates this violation entirely.