In rural parts of Texas, when you pass someone on the road, you wave at them ... or nod. Everyone does it! Kids not from the area get a kick out of it when they visit because they love waving at everybody.
On a side note ... this is a question for the ones that do not live in the states. Here in the US (in the places I have lived), when there is a funeral procession coming down the road, this is what it looks like: there is a hearse and all the cars behind it have their lights on to indicate they are with the procession. Sometimes the procession is escorted by the police. All the other cars on the road (on both sides) pull over to the side of the road until they pass. It is considered a sign of respect. Does this happen in other coutries? Just wondering.