State Mud Flap Requirements Guide

There are currently no federal regulations in the United States governing mud flaps or splash/spray suppression devices. Instead, these requirements are established at the state level, and the rules vary widely. Some states enforce detailed specifications for trucks, trailers, and buses, while other states have no specific laws at all.

The State Mud Flap Requirements Guide provides a searchable, state-by-state summary of current regulations for trucks, trailers and buses across all 50 states and the District of Columbia, as of July 12, 2025.

Overview of mud flap regulations

• No national (federal) requirements exist for mud flaps or splash/spray suppression devices.
• Each state determines its own requirements.
• Some states do not have any mud flap regulations at all.

State-by-state requirements

Access this Guide to find mud flap and splash guard requirements, including links to state resources, for:

• Commercial trucks
• Trailers
• Buses

Why compliance matters

• Safety: Prevents debris and water spray from impairing visibility for other drivers.
• Legal compliance: Avoids fines and penalties for non-compliance.
• Fleet maintenance: Reduces vehicle damage caused by road debris.

Keeping up with regulation changes

Regulations can change frequently. Always confirm details with the individual state’s Department of Transportation (DOT) before making compliance decisions.

Additional resources

• Mud flap requirements for commercial vehicles (article)
• Technical resources

FAQ

Are mud flaps required by federal law?
No. There are no federal-level mud flap or splash/spray suppression requirements in the United States.

Do all states require mud flaps?
No. Not all 50 U.S. states have mud flap requirements for commercial vehicles, but most do: in fact, it’s 42 of the 50. Meanwhile, Indiana, Kentucky, New Mexico, North Carolina, North Dakota, South Carolina, West Virginia and Wyoming do not (nor does Washington, DC).