[givc]

In US highways the exit ramp off the road is usually on the right, but is some cases the exit is on the left, especially in areas where the highway is elevated or in crammed downtowns. The left lane is also usually the “passing lane” and cars drive faster than on the right, so if there is a left exit and you’re cruising on the right line, you have to know in advance to safely move over to the left

[tylerflick]

Also High Occupancy Lanes will sometimes have their own exits on the left side.