What should a driver see in their rearview mirror before returning to their lane after passing another vehicle?

A driver should see the front of the vehicle being passed in their rearview mirror before returning to their lane after passing. This ensures that the driver has enough clearance to safely merge back into the lane. Once the front of the other vehicle is visible in the rearview mirror, it indicates that the driver has successfully created a safe distance between their vehicle and the one they just passed. This practice is crucial for maintaining safety on the road, as it helps prevent potential collisions that can occur if a driver attempts to change lanes without adequate spacing. Properly checking the rearview mirror is an essential step in the passing process to ensure that it can be done safely and without endangering any other road users.