United States Department of Transportation identification numbers are a required element on any vehicle that engages in interstate commerce of any kind, including passenger loads over eight people. These numbers help the authorities to identify the operating company and ensure that the business being conducted is legal. Displaying a DOT number is a relatively simple task.

Obtain a valid U.S. DOT number by submitting a completed form MCS-150 to the Federal Motor Carrier Safety Administration. This form must be submitted before the vehicle is operated.

Clean off any existing markings or identifying numbers so there is no confusion or blockage of the valid identifiers once applied. Mark each side of the commercial vehicle cab with the legal name of the controlling company.

Place 2-inch letters that spell out "USDOT" on the side of the vehicle beneath the company name. Immediately follow these letters with your U.S. DOT identification number in 2-inch numbers. The numbers and letters should be of a color that contrasts directly with the color beneath so they are clearly visible.

View the vehicle from a distance of 50 feet away. The letters and numbers that make up the U.S. DOT number should be visible clearly from this distance when the vehicle is not moving.

Place the operator's U.S. DOT number on both sides of the vehicle preceded by the words "operated by" if it is being used by anyone other than an employee of the controlling company.


You may or may not include the city and state of your business on the sides of the cab. It is not required by federal law.

You may use a magnetic or adhesive plaque to fasten your U.S. DOT number in place on the side of your vehicle, provided it does not move or negatively affect legibility.


If a U.S. DOT number is displayed in any way other than the described manner, the controlling company is subject to fines up to $11,000.