In the pre-digital days, especially scrappy musicians would visit record shop owners during their tours and convince them to carry their self-produced albums on consignment.

Then, on subsequent tours, the musicians would revisit these owners and collect their cut of the money.

Amy Ray knows all about this because she did it in the late ’80s as one half of the Indigo Girls, performing Sunday, November 15, at Detroit’s MotorCity Casino Hotel.

Ray said in a phone interview that she and her musical partner, Emily Saliers, worked hard in those days to build a grassroots following.

By the time they were signed to Epic Records, they’d built some leverage, Ray said.

“We knew that if things weren’t going well with the label, we’d leave the label and do it ourselves like we’d been doing,” she said. “I think that when you’re not living in fear all the time, it’s easier.”

Things came full circle for the Indigo Girls in 2007 when they exited a short and desultory stint with Disney and became independent artists again.

A lot had changed in the ensuing decades of course.

Ray said the “deep cut” fans that the duo cultivated in the ’80s – people who were more interested in listening to an album from start to finish than they were in hearing singles – are probably a vanishing breed.

“I think just the way we started helped us have this lifelong career,” she said. “Our approach has always been to try to keep evolving and to really care about our records instead of thinking, ‘Well, we’ve had a couple of hits. Let’s just play those over and over again.’”

It was not at all common in the pre-digital days for a label to leave artists alone and let them make the records they wanted to make, but Ray asserts that Epic and Hollywood Records (a division of Disney) really did leave the Indigo Girls alone.

“At that time we were signed, Epic was really considered a label that would develop bands,” she said. “Bands like Rage Against the Machine, Oasis and Pearl Jam. There were bands on that label that just kind of did their own thing, so we were in good company.

“Now, if it hadn’t worked and we weren’t getting anywhere,” Ray said, “I’m sure they would have come up with a gazillion suggestions for how we could improve ourselves.”

In the ’80s and before, getting signed to a major label was the goal of most dedicated rock and pop musicians because there really was no substitute for a major label’s promotions and distribution capabilities.

These days, it’s the major labels that are scrambling to stay relevant amid the democratization that is digitalization.

Yet, as easy as it is now to get your music out there, it can be hard to make yourself heard above the din (or to get paid within that din).

Certain things never change, Ray said. Like hard work.

“If you want be a songwriter – if you want to develop yourself as a song-oriented artist – you need to spend much time as possible writing,” she said. “You need to spend as much time as possible playing in front of people.

“That’s how you make it,” Ray said. “Tour as much as you can, play as much as you can and write as much as you can. There’s no shortcut.”

Ray loves how the digital age has given power back to the individual, but she said she hates how the corporate radio model has robbed stations of their local quirks.

“The biggest bummer to me,” she said, “is that – I love indie radio and I miss that excitement of a maverick DJ who would break bands. Now what’s breaking bands is very algorithmic. And there’s crowdsourcing too, of course. It’s interesting but it’s not what I’m used to, so I have to get used to it.”

The Indigo Girls have achieved about as much as any folk-pop group could hope to, but Ray talks about songwriting as if she hasn’t mastered it yet.

“It’s an endless pursuit,” she said. “It’s just one of those ‘you’ll know it when it happens’ things. I think it’s good to keep pursuing it. I don’t know where that mark is, but I know that I haven’t met it yet.”

One of the challenges of having such an extensive back catalog and such a devoted fan base is that concertgoers will periodically request songs of Ray’s that she wishes she’d written differently or had not written at all.

“That’s the hard thing because I just don’t want to play it,” she said, laughing. “Because I don’t think it’s a good song. You kind of have to figure out how to have a good, honest show – but also the audience is important.”

“You can’t be like ‘Screw you all. I’m just going to play whatever I want,’” Ray said. “Because that’s not the deal. That’s not really the partnership.”

Ray said it doesn’t take her long to figure out that a song she may have liked at one time isn’t up to her high standards.

“For me, it’s within a year of the release,” she said. “It’s not like ten years down the road I wake up and go, ‘You know? That’s not a very good song.’

“Sometimes, it’s like you’re really married to a song because it feels good to you,” Ray said, “and then you get out there and start playing it live and you realize it’s just not resonating.”

Becoming a better songwriter is, was and always will be the Holy Grail for both women, Ray said.

Saliers is currently working on her first solo album, Ray said, and she is also co-writing songs for sale to the country music market.

This may come as a shock to most people, but Ray and Saliers are fans of contemporary country music and think that some of the best songwriting today is happening there.

“I hate the production but I love the songwriting,” Ray said. “I have friends who do that and they have such a different thing going – the way they have of turning a phrase. If you strip away production and listen to the cleverness of song, it’s this thing where the craft still exists.”

The artistic space that the Indigo Girls give each other is intuitive, Ray said. They rarely have to have conversations about when it’s time to take a break.

Ray has recorded five solo albums, but she said she’s never harbored any illusions about a solo career eclipsing the Indigo Girls, nor has she had any interest in bringing such an eclipse about.

“We can go off and I can do my solo records but I know that’s my solo records,” she said, “ and it’s not the same as Indigo Girls and it won’t ever be as big. Or not even as big. As magical to me, even.”

Perhaps in her worst nightmares, Ray said she imagines what would happen if Saliers’ forthcoming country-inflected solo album is a Taylor Swift-sized hit.

“But then she’d be so rich she’d probably support me for the rest of my life,” she said. “So, you know, I could just play music and do my little hobbies.”

Ray said that she and Saliers have the sort of relationship where each knows the other will take care of her.

“Our partnership is like: we know that what we do together is not replaceable,” she said.