h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

It might bear mentioning that one pretty universal law for US drivers is that the slow traffic should stay to the right, and that passing is normally legal only on the left. Of course, inconsiderate or ignorant drivers make passing on the right a necessity on many occasions.

In Michigan, the only legal way to ask someone driving in the left lane to give way to passers is to honk your horn. I believe many other states have the same law. The problem is that many never learned it, so they will blink their lights, or brights, or otherwise try to get the offending driver's attention.

Many are wrongly taught that using the horn is either rude, or only for emergencies. The use of the horn is for communication; 'Hey, stop backing out of your driveway, I've got the right of way here', 'Excuse me, but I'd like to pass', 'Watch where you are steering that bicycle, your weaving in front of moving traffic', 'Don't come into this lane of traffic, I'm right here. There is no hole open', etcetera.

"It might bear mentioning that one pretty universal law for US drivers is that the slow traffic should stay to the right, and that passing is normally legal only on the left. Of course, inconsiderate or ignorant drivers make passing on the right a necessity on many occasions."

Also, in some states, including Maryland, passing on the right is perfectly legal.

I suspect that you'll find that passing on the right is legal in most states. In Europe, it's a bigger problem. Douglas Adams actually wrote something about it [A251182].

In Geogia, it would be illegal to use your horn to get someone to let you pass. Using high beams is a pretty standard way of letting someone know you want them to move over.