How exactly is this a 'feminist' film?

I agree with you, but I think maybe the reason people tout it as a feminist film is because the protagonist never gave in to the expectations of that place and all those dysfunctional people. The women pretty much got pregnant and had to get married, then live at the whim of their abusive husbands.
I think the most feminist line is when she's talking to her best friend whose husband won't let her use the truck to help go looking for the dad. The protagonist says something like, "I don't remember you ever eatin' any *beep* and the friend says, "It's different when you're married."

I think it just comes down to it having a strong female lead and being directed by a woman. There is nothing thematic that I can see that makes it feminist.

I think Scoochie has it right - she didn't submit and obey the way the women in her culture were expected to. Instead, she did what she had to do to save her family.

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I was a ballerina! Graceful! DELICATE!

In this movie Men bad, women good (okay only one woman is good, but it's a start). That's enough to qualify it as a feminist movie.

I guess if you have a movie where the female lead isn't a complete incompetent ditz, it's considered a feminist movie. That's why Gone Girl is considered a feminist movie, because the female lead actually knew what she was doing.

Its not feminist movie. The women are just as bad as the men. The movie is based on book. The author is from Missouri.