I’m talking about films (and novels and plays but mainly films) where there are a number of seemingly unrelated storylines that ultimately intersect with each other in various ways, usually as the denouement approaches. Examples would be Crash, Magnolia, Grand Canyon, and 21 Grams (and many more). This has come to be such a common storytelling device that someone must have come up with a name for it.
Thank you in advance for your help.
I’ve always heard them referred to as “Vignettes”
But you’re right, I think the “it’s all connected” genre really does need a word of it’s own.
I’ve heard the term “hyperlink cinema”:
Looking at the plot keywords for Short Cuts raises some possibilities:
Episodic
Multiple Storyline
How many examples can we name?
Babel
11:14
Pulp Fiction sort of fits, maybe.
Go is a bizzaro example of the genre. Instead of finally intersecting at the end, all the storylines intersect in the beginning.
For some reason the term tapestry comes to mind. I’m sure I’ve heard such films being referred to like that before.
How about “disjointed”?
Before the term “hyper-link” existed, I believe they called it “jigsaw narrative,” but I can’t remember where I saw that.
Terry Pratchett uses this device. And I’ll echo, I don’t know of any particular word for it. Smarter people than myself need to get busy.
Almost every episode of Seinfeld. 
This is only my own term and not an industry/official one, but I call them “stir fry stories”. (If you’ve ever cooked stir fry you know that first you do the broccoli, then take it out and do the water chestnuts, then the meat, etc., before finally putting them altogether.)
“Tired”?