USDOT Number Display Rules for Trucks
This is a plain-language summary of the federal marking rule in 49 CFR 390.21. It is not legal advice. Rules differ for some vehicles and states, so always confirm your own requirements with the FMCSA and your state before you order.
What the rule asks for
The federal marking rule is 49 CFR 390.21. It says a motor carrier's commercial motor vehicle that is subject to the federal safety rules shows two things: the legal name or a single trade name of the carrier operating it, as listed on its FMCSA registration (Form MCS-150), and its USDOT number, preceded by the letters "USDOT". If another company's name also appears on the vehicle, the operating carrier's name and number follow it, preceded by the words "operated by".
Color and visibility
The rule asks for letters that contrast sharply in color with the background they sit on, and that are readable in daylight from a distance of 50 feet while the vehicle is stationary. The marking also has to be kept up so it stays that readable. The rule does not set a minimum letter height in inches, so the 50-foot test is what counts. Black or white lettering on a plain, light or dark door is the simplest way to get strong contrast.
Both sides of the truck
The marking goes on both sides of the self-propelled vehicle, so a truck or tractor usually needs two matching decals, one for each door. It can be painted on or be a removable device, such as a magnetic sign, as long as it meets the same contrast, readability and both-sides requirements. The rule covers the power unit rather than a towed trailer. Our decals are priced per decal, so order a quantity of 2 for a pair.
City, state and MC numbers
The federal rule does not require a city and state, although it does not prohibit them either. FMCSA also says no federal marking requirement exists for displaying an MC number on a truck. Many carriers add one anyway, and you can show other identifying information as long as it does not conflict with the required name and USDOT number. Some states ask for their own numbers as well, such as a California CA number, Kentucky KYU or Texas TXDOT. Check with your state agency for your own requirements.
Go deeper
- How big do USDOT numbers need to be? for the 50-foot test and how to check your own door.
- Where to put the USDOT number on a truck for a placement checklist.
- Who needs a USDOT number? for the weight, passenger and hazmat tests.
- MC number on a truck and MC number vs USDOT number.
- USDOT number requirements by state for state numbers such as CA, KYU and TXDOT.
- How to get a USDOT number and how to look one up.
- All guides and decals by vehicle.
Regulation number decals
We make MC, CA, KYU, TXDOT, GVW and VIN lettering as single numbers or as stacked sets. See our regulation number decals.
Choosing the right decal
- Just need the number? See the USDOT decal.
- Want name, city and numbers together? See the Custom USDOT Logo.
- Want to see it first? Try the live door builder.