After watching the film a few times and enjoying the strangeness and ambiguity, it finally clicked as to why I enjoy the film so much. It's about something quite universal and offers a fresh insight into something that is an integral part of our culture: Motherhood.
If you haven't seen the film, stop reading. If you've seen it, bear with me. Many people have talked about the 'personality swap' that takes place between Pinky and Millie. That never rang true to me. They certainly don't swap personalities, although Pinky exhibits a new personality after she jumps into the pool.
This film is simply about what a mother experiences as her daughter grows into a woman. And so many details and moments in the film say volumes about the painful realizations and feelings that many mothers go through, feelings that have never been dramatized as creatively as Altman has done here. For this reason alone, this film is a gift.
Millie is introduced as a bit directionless, always trying to fit in, but never garnering the attention, respect or love she longs for. He coworkers ignore her rants, her neighbors dismiss her, and her former roommate blows her off. But along comes Pinky, strangely childlike considering her apparent age. She is simply the daughter that enters this lonely woman's life. Not literally, but none-the-less, the relationship proceeds this way. Millie is suddenly the center of her new daughter's universe. We see Millie blush at the attention and adoration she has never received. Like any mother, Millie is constantly guiding and teaching Pinky the proper protocol for every situation - from what to wear, daily routine, entertaining guests--and Pinky absorbs it like a sponge. For many of us who love the film, there has always been something very relatable about the way they connect, even if it's hard to put your finger on.
But the dynamics shift when Pinky goes through a symbolic puberty (jumping into the pool). Not coincidentally, this shift is set off by Millie's betrayal of the 3rd woman (Willie, symbolically the grandmother in some respects). After coming out of a coma, Pinky is suddenly a sexual being. Watching how Millie reacts to the new Pinky is quite illuminating, considering that most parents experience this surreal process during their life. The mother has to watch her daughter blossom and have it rubbed in her face that she is past her own sexual prime (this is dramatized by the way neighbor Tom gives Pinky the attention Millie never was able to get). The Mother has to see her own bad habits and traits reflected back via her daughter's behavior (Pinky's new smoking habit and garish use of makeup). And most painfully, the mother falls of her perch as center of her daughter's universe. For those of us who appreciate the film, this is the real heart of the watching Shelley Duvall and Sissy Spacek go through the surreal turns of this story. It is something absolutely universal. Something our parents silently went through as we became new creatures in our blossoming adolescence.
By not presenting Millie and Pinky as literal mother and child, Altman may alienate some less-discerning viewers. But what he achieves is worth it: He presents how surreal and alienating these parts of the parenting process are. It's a mysterious shift in balance of power, in focus of affection, in bond, and it ultimately leads to a disturbing realization... something that can't be expressed in a self-help book or a parenting manual, but it's hauntingly expressed in the still-birth sequence at the end.
The strange coda to the film, which shows the 3 women working at Dodge City with all male interference cast aside, has also baffled viewers. But I would argue that Altman smartly used this ending to provide a key to understanding the film. In this final scene, the women are blatantly portrayed as a family: Willie is cast as the grandmother, Millie as the mother, and Pinky as the daughter. It feels very different in tone than the rest of the movie: more theatrical and symbolic. This coda kept encouraging me to revisit the film and puzzle through its mysteries. Many reviews on this site insist that there is no method to Altman's madness. I would argue that it's an example of his genius. He may not have even defined them exactly as mother/daughter in his mind, but he was certainly interested in portraying truth, and that essential truth has made this a beloved film, even for those who prefer not to dissect it.