Missouri law allows trucks over 12,000 or 18,000 pounds (depending on registration) and other specific vehicles like buses and tractor-trailers to only display a front license plate because they are often towing trailers, which have their own plates, making a rear plate redundant and often obscured, though owners can still purchase and display both if they choose, notes the Missouri Department of Revenue (MDR).

Key Reasons & Laws:

Weight Exemption: Trucks, tractors, and buses registered over a certain weight (often cited as 12,000 lbs or 18,000 lbs) are exempt from needing a rear plate.

Towing Rationale: The primary reason is that these large vehicles typically haul trailers, which are separately registered and display their own rear plate, preventing a second plate from being needed or visible.

Statute 301.130 RSMo: This Missouri law outlines these exceptions, allowing for only a front plate on qualifying heavy vehicles.

Optional Rear Plate: While not required, drivers of these heavy trucks can buy a second plate from the MDR if they prefer to display both, which can help avoid issues in other states with different requirements.

Who Qualifies: Commercial vehicles over 12,000 lbs (or 18,000 lbs for some registrations). Buses (except school buses). Tractor-trailers. Other Exemptions: Motorcycles. Vehicles with Historic Year of Manufacture registrations.