DOT marking identification - Iowa

Iowa has adopted 390.21 of the Federal Motor Carrier Safety Regulations (FMCSRs), as it existed on October 1, 2025.

Section 390.21 applies to commercial vehicles with a gross weight or combined gross weight of 10,001 or more pounds, as well as to commercial vehicles with a gross vehicle weight rating or gross combination weight rating of 10,001 or more pounds. Vehicles transporting hazardous materials requiring placarding are also subject.

Section 390.21 does not apply to combination vehicles provided the gross vehicle weight rating of the power unit is 10,000 pounds or less and the gross combination weight rating is 26,000 pounds or less.

For-hire carriers operating commercial vehicles in intrastate commerce are required to mark the power unit with the operating motor carrier’s name and USDOT number.

Intrastate private carriers are not required to obtain a USDOT number. According to the Iowa DOT’s Office of Motor Vehicle Enforcement, no warnings or citations will be issued for intrastate private carriers not displaying a USDOT number.

The US DOT number must have the suffix “IA” if the carrier is an intrastate only carrier.

Example: USDOT 123456 IA