I can attest that people also wave at boats. And truckers, motorcycles, riders of horses, pretty much any novel vehicle they come across wherever they are. People are friendly and happy to see a traveler coming through. Cars are much too ordinary now, but I’m sure there was a time people waved at them too.

@1 -- Yes, it is a novelty thing, although I think Megan is right as well. I've sat on a dock on a busy, sunny weekend (like this) and watched as boats pass by the Montlake Cut. It seems silly to wave to each other, but it is clear we are also looking at each other. One of us on the dock made a halfhearted wave, then someone on the boat did the same. That was followed by someone on the boat enthusiastically waving, because, why the fuck not? It was a nice day and they had been drinking; might as well wave to strangers. Its the same reason people wave in parades.

Only a churlish rube would take offense at someone waving at them.

No need to make it complicated.
People wave at trains because it’s fun.

This rant reminded me of the time that Dan Savage ranted about airplane passengers who dare spend any time looking out the window (he thinks it's a complete waste of time and wants the window shade shut all the time).

In any case,

Charles, you wrote "She waved at me". How exactly do you know that she was waving specifically at you? There's a long tradition of waving at the engineeer/conducter and in the old days of waving at the caboose people. Did you grow up seeing cabooses? How do kids perceive long-gone cabooses nowadays?

So yeah, you could have gone into how you assumed they were waving at you instead of at a person one railcar away. Maybe there was someone in that other railcar wildly waving and the ground person was responding to that. Turn it into some philosophical center-of-the-universe thing.

@5 nails it. Ya gotta wonder when someone projects on others that they are are having a nervous breakdown upon a simple show of friendliness... Who exactly is having a nervous breakdown here?

Amtrak’s “California Zephyr” runs along the Colorado River in Colorado, and in the summer it’s a tradition for the rafters on the river to moon the train. It’s called the “Amtrak Salute”, and the train crew always call attention to it. I can’t imagine what Our Dear Charles would make of that.

Actually, it stems from the railroads' requirements that their employees on the ground observe the train for signs of overheated wheel bearings and other defects that the engineer can't readily see. If things look good, the arm is raised (the "high ball" signal). If bad, you move your arm horizontally, like a stop signal. Over time, the "high ball" became just a plain waive. Nerdy answer for sure.

@1 Yes, I remember my grandmother saying that when she was a young child (this would've been about 1910) whenever she and her friends heard a car coming, they'd run to the road to wave at the driver and watch it go by.

Can it be something as simple as someone (dear) wanting to say, "Howdy, friend! Enjoy your trip?"

Let's please don't be so sophisticated that we turn our noses up to a moment of thoughtfulness.

waving
(saying)
'I See You'
recognizes
acknowledges
your & my Humanity.

'thanks for not running over me!'
is my favorite wave walking
alongside a motorway

pass by too closely
you get the One
finger Salute:

yes you May be
a human being
but you're also
an Asshole