Can Large Trucks Drive in the Left Lane in California?

by Staff | March 13th, 2024

In the U.S., the left lane is the passing lane or the “fast” lane. Drivers typically use the left lane to pass other vehicles. In California, lanes are numbered from left to right, with the number “one” lane being the leftmost lane. Drivers of standard passenger vehicles are advised to stay in the far-right lane when moving slower than other vehicles and to use the left lane for passing slow moving traffic.

Considering their relatively slow speeds, you may be wondering if semi-trucks can use the left lane. Read on to discover what the law says about large trucks driving in the left lane in California and learn about the potential risks and dangers.


Legislation regarding driving in the left lane in the U.S. varies by state. Four categories exist:

  • “Keep right” states: Driving in the left lane is prohibited except for passing or turning left.
  • “Yield” states: Driving in the left lane is tolerated, but drivers must yield and move to the right lane if they are blocking traffic.
  • “Keep right when slower” states: These states follow the recommendations outlined in the Uniform Vehicle Code. According to UVC 11-1205, while drivers can cruise in the left lane, they should keep right if they are slower than the current traffic speed (regardless of the speed limit).
  • Permissive states: Driving in the left lane is allowed without restrictions.

According to the California Vehicle Code (CVC 21654(a)), the Golden State follows UVC recommendations, making it a “Keep right when slower” state. Left-lane driving is generally legal as long as the driver doesn’t impede traffic.


The California Vehicle Code oversees numerous commercial vehicle laws and regulations, including those governing semi-trucks. One of California’s most critical laws that semi-trucks and other large vehicles must follow is vehicle-specific speed limits.

According to CVC 22406, large trucks (also referred to as motortrucks) are among the six categories of vehicles prohibited from exceeding 55 miles per hour on a highway.

Other vehicles may use the left lane to drive at speeds up to 65 mph (CVC 22349) or 70 mph (CVC 22356), depending on the posted speed limit.

In practice, these speed limits mean trucks are not legally allowed to exceed 55 mph anywhere on the highway. Therefore, they would be highly likely to impede traffic behind them if they switched to the left lane.

Another law (CVC 21655) stipulates that any vehicle subjected to the speed limits of CVC 22406, like semi-trucks, must stay within designated slow vehicle lanes at all times unless turning left or preparing to enter or exit the highway.

  • 2-lane and 3-lane highways: The designated slow vehicle lane is the rightmost lane.
  • Highways with 4 or more lanes: The designated slow vehicle lanes are the two rightmost lanes.


Some highway sections may feature truck-only lanes, reserving traffic for large commercial vehicles and prohibiting passenger cars from driving on them. Drivers can easily recognize these lanes by looking for the white signs stating TRUCK LANE, TRUCK TRAFFIC, or Trucks/All Trailers in black text.

The end of the truck-only lane zone is marked by another sign: END TRUCK LANE RESTRICTIONS.

You can find examples of truck-only lanes at the following locations:

  • At the I-5 / SR 99 junction in Kern County (southbound only)
  • At the I-5 / SR 14 junctions in LA County (northbound and southbound)


According to Federal Motor Carrier Safety Administration (FMCSA) data, there were 168,320 truck crashes in the U.S. in 2022. 13,603 of these crashes happened in California, which is more crashes than in any other state besides Texas. And when semi-trucks cause crashes, 83% of the time the person injured is someone other than the truck driver.

Not only is it illegal for a truck to leave its designated lanes, but California’s 55 mph speed limit on large trucks prevents them from legally reaching the speeds necessary to pass vehicles on the highway. Driving in the left lane would impede traffic flow, create congestion, and significantly increase the risk of causing accidents. Moving any faster would constitute speeding, further increasing the potential risks.

Potential risks associated with trucks in the left lane include:

  • Trucks occupying the left lane may not reach sufficient speeds to pass vehicles on the right, impeding traffic flow. Traffic congestion increases the risk of rear-end accidents.
  • Vehicles behind a truck changing lanes may brake suddenly, significantly increasing the risk of rear-end accidents.
  • Vehicles flowing in and out of the truck’s blind zone as it switches lanes may be side-swiped or struck.

Roughly a third of all truck crashes result in an injury.  


Truck accidents often cause severe, life-threatening injuries. If you or one of your family members are involved in a truck accident, contact the California truck accident lawyers at Berg Injury Lawyers for a free consultation today. We can help you hold the trucking company accountable and get the compensation you deserve.

Originally published March 28, 2022.