**most excellent topic**
I always thought the black hat/ white hat issue had to do with the ying and yang idea. The idea that Ennis and Jack are "opposites" but rely on one another and each also contains a little bit of the other.
It's nice that the hats in the background aren't always consistent. It would be too much if all the hats in the background of Jack were always white, and vice versa. I think we just see Jack in crowds a lot more than we do Ennis. And on a simple level, this explains why there are more hats (of each color behind Jack). I mean, Jack goes to busy, crowded bars (Ennis goes to pretty small, lonesome bars), Jack is a performer (and is surrounded by lots of crowds at the rodeo), goes to "proper" dinner dances with Lureen and other couples, etc. Jack is simply more social and "worldly" (in that he travels, seeks out companionship etc., while Ennis tries to hide from people, and doesn't seem to seek out the same social atmospheres as Jack). However, for both Ennis and Jack, I think there are significant moments when background hats and their colors are
really symbolic and important. There are lots, but I'll just mention a few for now.
-I think the key example is in the Cassie/pie scene at the bus station. Many people have noted the poignant detail of the two men (one in a black hat and one in a white) at the bus counter buying a ticket and getting out of town. A sad reminder of what Jack and Ennis
could have done together.
-One of my favorite moments of Ennis and a black hat is in the scene where Alma Jr. is watching Ennis and Cassie dance. The only other couple dancing near them is a man in a black hat and a woman with lots of tattoos. The man in the black hat is tilting his head in such a way that he looks like a "generic" guy in a black hat... It seems like a big clue about what's on Ennis's mind. Almost like a thought bubble in a cartoon...
-An interesting and complex moment with Jack and background hat colors is in the Jimbo bar scene. Clearly Jack seems attracted to Jimbo as a kind of "Ennis substitute" made clear by the white hat (the freaky,
too white hat) and the white shirt. When Jimbo rejects Jack and walks to the pool table his buddies close in around him to listen to what he's saying... and in that group there are two black hats and two white hats. I don't know exactly how to read that, but I've always noticed it. Ever since my first few viewings.
-And, regarding Jack and white hats... People have noticed that at the rodeos there are often an abnormally large number of guys in white hats in the stands. Also when he's selling tractors there are often mostly men with white hats.
OK, I'll stop before I go on and on about the man in the white hat that walks out of the frame behind Ennis during the parting conversation with Jack during the Brokeback summer while Jack and Ennis are leaning on the black truck...