Washington's primary keep-right law is found in RCW 46.61.100.
On roadways with two or more lanes available for traffic moving in the same direction, vehicles generally must be driven in the right-hand lane available for traffic.
A driver may use another lane when overtaking and passing another vehicle, when traveling at a speed greater than the existing traffic flow, when moving left to allow traffic to merge, or when preparing for a lawful left turn at an intersection, exit, private road or driveway.
Washington also specifically makes it a traffic infraction to drive continuously in the left lane of a multilane roadway when doing so impedes the flow of other traffic.
Vehicles or combinations weighing more than 10,000 pounds are generally required to use the right-hand lane except under the same statutory exceptions.
On limited-access highways with three or more lanes moving in one direction, vehicles towing trailers and vehicles or combinations weighing more than 10,000 pounds generally may not use the left-hand lane, except when preparing for a lawful left turn or when another statutory or regulatory exception applies.
Exceptions
- Overtaking and passing another vehicle traveling in the same direction.
- Traveling faster than the existing flow of traffic.
- Moving left to allow traffic to merge onto the roadway.
- Preparing for a lawful left turn at an intersection, exit, private road or driveway.
- Avoiding an obstruction or roadway hazard when moving left is necessary and safe.
- Using another lane when authorized by traffic-control devices or applicable highway regulations.
Penalties
Continuously driving in the left lane of a multilane roadway while impeding the flow of other traffic is classified as a traffic infraction under RCW 46.61.100.
The total amount due may include the applicable base penalty and statutory assessments. Drivers should verify the current amount shown on the citation or through the Washington court handling the case.
Official Source
Last verified: October 11, 2026