I drive a truck. (That'll be important later.)
Here in Texas we have a wave that's actually known as the "Texas Wave." It involves lifting only two fingers from the steering wheel to greet an oncoming driver.
In driving about 2000 miles the past few weeks, I've notice fewer returned Texas waves and far too few oncoming-driver initiated waves. Which led me to think it could have been the area of the state or the vast amount of imported drivers from, say, Oklahoma or some other less-friendly place.
But, for the sake of discussion, let's say that simply crossing into Texas should be enough to adopt our friendly driver greeting.
In Texas, we have interstate highways, U.S. highways, state highways, loops and spurs, farm-to-market roads, business routes, ranch roads, park and recreational roads, toll roads, city streets and residential streets. Admittedly, while driving on I-20, I-35, Hwy 360, I don't wave to greet oncoming neighbors because I'd have to leave two fingers in the air constantly due to the amount of oncoming people I want to befriend.
I just removed interstates and U.S. highways from the required waving zone. Perhaps, because it stretches beyond our boarders and we can't guarantee the type of people we meet … or maybe due to the heavy travel. But, beyond those, on what type of roads does the Texas wave begin and end? Is there a vehicle-per-hour limit that allows us to not wave at oncoming passengers?
If all of this is too confusing and you don't want to wave or wave back – the solution (other than move to a different state) is to drive a small sports car.