<P> Most commonly, motorists will attempt to overtake the outer car on the inner lane either to continue at a fast pace or to pass a car that is going too slowly in the passing lane . On high - capacity multilane freeways (three or more lanes per direction), many motorists often pass on the inner lane, largely in response to misuse of the "passing lane" by slower traffic . </P> <P> In some areas, such as the US states of Colorado and Kentucky, vehicles in the left lane are required to yield to faster traffic only if the speed limit is above 65 miles per hour . In other areas, like Alaska, there is no law requiring slower traffic to move over for faster traffic . </P> <P> The use of passing lanes for faster traffic is sometimes acknowledged with signs using phrases such as "Slower Traffic Keep Right" (in Canada, where the passing lane is to the left). In a study by the AASHTO Subcommittee on Traffic Engineering, all 24 US states involved used some form of passing lane courtesy signage, 9 of which only use those signs for steep graded roads . </P> <P> Many areas which make it illegal to fail to yield to faster traffic also have exceptions to those rules . Some of these exceptions include preparing to make a left turn, taking an exit located on the left side of the roadway, avoiding traffic merging onto the roadway, or overtaking and passing another vehicle . </P>

Which lane is the passing lane in canada