On a four-lane highway, the left lane should only be used for?

On a four-lane highway, the left lane is designated primarily for passing other vehicles. This allows for smoother traffic flow and prevents congestion in the right lanes, which are typically used for slower-moving traffic and general travel.

Using the left lane for passing is not only a standard traffic rule but also promotes safety on the highway by allowing faster vehicles to overtake slower ones without causing disruptions. Drivers should maintain awareness of their surroundings and return to the right lane after completing a pass to ensure that the left lane remains clear for others who may need to pass as well.

Other potential uses of the left lane, such as driving slowly, exiting the highway, or parking, can lead to hazardous conditions and impede the traffic flow, which is why these practices are discouraged. By keeping the left lane reserved for passing, it helps maintain a more efficient and safer highway driving environment.