§390.21 requires every self-propelled CMV operated by an interstate motor carrier (and any intrastate carrier whose state requires a USDOT number) to display, on both sides of the vehicle:
- The legal name or single trade name of the motor carrier as listed on the MCS-150
- The motor carrier identification number preceded by "USDOT"
- Markings in letters that contrast with the background, readable from 50 feet during daylight
Operational implications
Missing or improper §390.21 markings are a common pretext for a roadside CMV inspection. Officers verify carrier identity against the SAFER database during the stop; mismatched markings (DBA name vs. legal name, transcription errors in the USDOT number) extend the inspection.
Common findings
- USDOT number on the vehicle doesn't match the carrier of record (frequently leased operators)
- DBA name displayed without the legal name from the MCS-150
- Markings too small (the 2-inch lettering requirement is the typical minimum to meet "readable from 50 feet")
- Markings have peeled or faded to the point they can't be read at 50 feet
How to prevent it
- Update vehicle markings whenever the legal name on the MCS-150 changes
- Leased operators: verify the carrier of record markings match the actual carrier authority being operated under
- Photograph each vehicle's markings at acquisition for the audit binder
How Roadworthy HQ helps
Roadworthy HQ does not track vehicle markings; there is no markings date or photo on the vehicle record. Roadside inspections are logged on the vehicle (date, state, level, driver, number of violations, out-of-service or not), and an out-of-service inspection starts the 15-day §396.9(d)(3) repair-certification countdown.