MC Number on Truck: Is It Required on the Door?

The MC number on truck doors is not required by the federal marking rule. FMCSA's guidance says that no marking requirement exists for display of the MC number of a U.S. carrier (FMCSA). The rule asks for the operating carrier's name and USDOT number, and nothing more.

You are still allowed to show an MC number, and many carriers do. This guide covers where the old habit came from, what you may add, and how to lay it out so it helps rather than clutters.

What FMCSA says today

The marking rule lists the legal name or single trade name of the carrier and the USDOT number preceded by the letters "USDOT" (49 CFR 390.21). An MC number is not on that list. You may see websites list the MC number as required lettering. The FMCSA guidance above is the source to trust, so use it to settle the question.

The MC number is a different record from the USDOT number. If the difference is fuzzy, read MC number vs DOT number first.

Where the MC number habit came from

Before 2000, carriers with authority from the Interstate Commerce Commission displayed an ICC docket number, the MC number, on both sides of each power unit. FMCSA's June 2000 final rule eliminated those old marking rules and required the USDOT number on both sides of power units. Carriers already marked with an ICCMC number had until July 3, 2002 to switch (Federal Register, FMCSA highlights).

So the habit is older than the current rule, and it never had to stop, because showing one is still allowed.

Is showing one allowed?

Yes. The 2000 rule does not require carriers to remove an MC number, although FMCSA encouraged them to refrain from showing it on new or repainted vehicles once the rule was final (Federal Register). The current rule also allows other identifying information if it is not inconsistent with the required name and number (49 CFR 390.21).

That "not inconsistent" test is the practical limit. The MC line must never look like part of the USDOT number or make it harder to read.

When adding it makes sense

It is your call. Common reasons carriers add it:

• A customer or a lease agreement asks to see it on the door. That is a business arrangement between you and them, not a federal rule.
• You want the truck to carry the same identifiers you quote on paperwork.
• You are matching other trucks in your fleet.

If you have no operating authority, you have no MC number to show. Private carriers hauling their own cargo generally do not need one, as explained in our MC vs USDOT guide.

MC number display requirements: size and format

Since the rule does not require the MC number, it sets no size for it either. The test for the required lines is that letters contrast sharply and are readable from 50 feet in daylight while the vehicle is stopped (49 CFR 390.21). It makes sense to hold an MC line to the same standard, so it reads as well as the line above it.

For the format, keep it plain:

• Write the letters MC, then your number, as it appears on your authority record.
• Give it its own line under the USDOT line so the two numbers do not run together.
• Use the same lettering color as the rest of the decal.

You can check your number on the FMCSA Licensing & Insurance search. Our USDOT number lookup guide shows how.

Where it fits on a door decal

There are two simple layouts. Our USDOT + MC two-line decal puts USDOT on the first line and MC on the second, on one rectangle. If you already have a USDOT decal and want to add the line later, the MC Number decal is a single-number decal.

Each decal is priced per decal, so order two for both doors, and pick 12, 18 or 24 inches wide. Those are decal widths, not legal letter heights. In the door builder, an MC line adds $4 per decal, and a live preview shows the decal on a truck door before you order.

On a semi or a trailer

On a tractor-trailer, the marking duty sits with the power unit, so the lettering belongs on the tractor doors. A trailer is not covered by the marking rule, as we explain in DOT requirements for trailers. Some states ask for their own numbers as well, and those are separate from the MC number (state requirements).