The Sudden Rise of Zach Bryan

One of the year’s biggest pop breakouts is Zach Bryan, a Navy veteran who makes calm and detailed country-folk. His major label debut album, “American Heartbreak,” has steadily held in the Top 20 of the Billboard album chart since its release in May.

Bryan is not a radio fixture, and mostly has found success on streaming, translating into live crowds of several thousand per night. He is also a reluctant star, offering very little to the public outside of his music and Twitter feed.

On this week’s Popcast, a conversation about Bryan’s old-fashioned artistry and 1990s attitude, the shifts in mainstream country music that have in part set the table for his rise and how genre boundaries serve as guideposts, even for artists who assiduously try to skirt them.