Missouri's primary keep-right rule is found in Revised Statutes of Missouri §304.015.
On highways with two or more lanes of traffic moving in the same direction, vehicles generally must be driven in the right-hand lane.
A driver may use another lane when overtaking and passing another vehicle, preparing to make a proper left turn, or when traffic markings, signs or signals direct otherwise.
Missouri also has a separate slower-traffic rule. A vehicle traveling at less than the normal speed of traffic generally must use the right-hand lane available for traffic, or stay as close as practicable to the right-hand edge or curb.
Missouri law also requires a driver being overtaken to give way to the right in favor of the passing vehicle, except where passing on the right is legally permitted.
In addition, trucks registered for a gross weight of more than 48,000 pounds generally may not use the far-left lane on interstate highways, freeways or expressways within urbanized areas when there are three or more lanes traveling in the same direction.
Exceptions
- Overtaking and passing another vehicle traveling in the same direction.
- Preparing for a lawful left turn.
- Following traffic markings, signs or signals that direct use of another lane.
- Using another lane when the roadway configuration or traffic-control system lawfully permits it.
Penalties
Violations of Missouri's keep-right and lane-use rules may result in a traffic citation. The exact fine and total amount due can depend on the specific subsection charged, the court handling the case and applicable court costs.
Missouri's related passing statute, §304.016, classifies violations of that section as a class C misdemeanor.
Drivers should verify the amount shown on the citation or with the court handling the case.
Official Source
Missouri Revised Statutes §§304.015 and 304.016 - Keep Right and Passing Rules
Last verified: October 11, 2026