The nice folks over at PBS were kind enough to give me an exclusive sneak preview of “Loretta Lynn: Still a Mountain Girl,” which airs as part of “American Masters” this Friday. It’s an excerpt from the movie about the way Lynn created space for other women in country music by singing honestly about the realities of her life and women’s experiences.

Specifically, the clip addresses Lynn’s song “The Pill,” recorded in 1972 and released in 1975, which was so controversial that some country radio stations declined to play it until it became a commercial success. Lynn’s satisfaction at the stations’ capitulation is evident in the clip. And it’s worth listening to the whole song to appreciate just how radical “The Pill” is.

“The Pill” has an edge of anger to it, which makes sense; it’s a dispatch from a time in the not-so-distant past when American women couldn’t control their own fertility and their lives were harshly circumscribed as a result.

“Promised if I’d be your wife / You’d show me the world,” Lynn sings. “But all I’ve seen of this old world / Is a bed and a doctor’s bill,” due to her frequent pregnancies. But the song is funny and joyful, too; Lynn jokes that “This old maternity dress I’ve got / Is goin’ in the garbage / The clothes I’m wearin’ from now on / Won’t take up so much yardage.”

It has become easy to dismiss sexual liberation as a frivolous or self-indulgent concern. But in a single song, Lynn captured the full measure of change that revolution wrought in a single lifetime.

“Say what you will, but she’s a feminist. And she made it OK for other women to go ‘Yeah!’ (in recognition.) That’s the way movements start,” Sissy Spacek, who won an Academy Award for playing Lynn in “Coal Miner’s Daughter,” the 1980 adaptation of Lynn’s memoir, says in “Loretta Lynn.” And Sheryl Crow, who credits Lynn with making her career possible, marvels at the transitions Lynn depicted in her music: “She wrote about what it was like to be a woman who was making the transition from barefoot, pregnant and in the kitchen to being a working woman.”

Much of the power of Lynn’s songs comes from the fact that they are blunt, rather than aspirational, whether she’s singing about the most difficult parts of her marriage to her husband, Oliver (better known as Doolittle), her family and her heritage, or even the pleasure she takes in a sloe gin fizz. Reba McEntire told me that she was inspired by Lynn’s stage presence, particularly the way she insisted that her songs were true to her life and why she stayed in a difficult marriage.

“The honestly I saw in her songs gave me the confidence and the honesty in myself to go out and when I do interviews, if I did something, to just say it,” McEntire reflected. “That honesty, that blatantly blunt honesty, endeared me to her. People will say, ‘Why did you stay with Doo so long?’ She would say, ‘I wouldn’t be where I was today without him.’ “

And while McEntire has not written the majority of the songs she performed, in the aftermath of her divorce, she took inspiration from the way Lynn turned difficult emotions and personal experiences into music and processed them through her art.

“My last album, I just went through a divorce, and the album’s all about that. I’d have to think about that. I know Kelly Clarkson, my daughter-in-law, before she got married and now is just deliriously happy, all she sang about was sad songs and the situations she’s in. So now that she’s happy, she says it’s going to be really hard to write a sad song,” McEntire told me. “I think I’ve written more songs in the last nine months than I have in my entire life ... Music is so healing. It’s the best way in the world to help you get out of a situation.”

She has felt that way for a long time. Growing up, McEntire’s family both competed and sang at her local rodeo, which is where she saw Lynn for the first time.

“All the country songs that I used to sing dealt with very adult situations and topics even as a kid. I told Mom and Dad, ‘I couldn’t believe you let me sing those songs when I was a kid!’ “ particularly one track about a young woman who turns to prostitution,” McEntire recalled. “She said, that’s just the way of life, Reba. You can’t get away from that. It’s not all roses. ...

“We would watch every act that would come in there. I’ll never forget. I whooped off my cowboy belt and got her to sign it for me,” McEntire said. “We were behind the bleachers, and she was on her way back to her bus. We didn’t have pictures or anything to give her. Mostly it was our belts or boots.”

Lynn’s honesty and openness weren’t merely musically inspiring; these characteristics played a political role, expanding the range things women artists could say in public.

“I think one of the things that Loretta did for all female songwriters was actually write about what was happening at the time, whether it was a popular topic for a woman to be talking about or not,” Crow told me when we spoke by phone last weekend. “She went out and performed those songs on really well-known live TV variety shows. ... She was really fearless about it, and yet she kept her sense of humor. She was so intelligent about the way she wrote those songs, and she kept them down-home enough for everyone to relate to.”

Crow pointed to Lynn’s influence on one of her own early songs, “What Can I Do For You?” which is written from the perspective of a man who is offering to help a young woman with her career in exchange for sex. The song, Crow reflected, describes “a very intense situation of sexual harassment, and though the song is pretty funny, it’s sort of when I think of it, in the tradition of Loretta. It’s simply telling the story, and she was brilliant in the way she could do that and draw everyone into what she was writing about. She was really the architect of doing that in female song-writing.”

Crow said she had been disappointed to see fewer artists take advantage of the freedom that artists like Lynn had won for them, and the way tending an artist’s brand has become an all-consuming preoccupation.

“I don’t know very many artists that are really hitting it commercially that are willing to write about what’s really happening. Our artists in the ‘60s would do that. And now there’s more presence of branding and what you represent to your fans,” Crow said.

“Just in the last few weeks, watching what’s going on with Beyoncé. She had a strong and very orchestrated brand, and for her to stick her neck out there to make a statement that I’m assuming that she believes in, it’s almost as if people are shocked that she would have something to say. We need to get back to that, to where we expect our artists to speak for us.”

Lynn may have been personally courageous, but she had a community behind her. “Loretta Lynn: Still a Mountain Girl” is a lovely chronicle of Lynn’s friendships, starting with Patsy Cline, who gave Lynn clothes when she moved to Nashville and taught her to wear makeup. “I wore a pair of panties she gave me for four years,” Lynn reminisces of Cline’s generosities; Tim Cobb, who designed Lynn’s museum, says the underthings are still in the archives.

McEntire says she had a similar experience, minus the hand-me-downs.

“I came from a rodeo background into the music business where I didn’t know anybody. People were very protective and very nurturing, and they taught me. And thank goodness it went so slow,” she said, tracing her trajectory. “I didn’t have a No. 1 single until January of ‘83. I had a lot of great teachers to teach me about the business. ... You showed respect for the people who came before you because they paved the way for you. They found a better way of doing things.”

McEntire said that respect for tradition tied even a crossover artist such as Taylor Swift back to her country roots. And the community of country musicians means that women who want to can forge much longer careers than they might in other more disposable genres.

“I just love the business,” McEntire said. “Loretta does too. So does Dolly (Parton). I’ve asked Dolly when do you think she’s going to retire. She’s about nine years older than me. She says, ‘What would I do?’ “