The lines in their faces had more to say than all of Carrie Underwood’s No. 1 power ballads.

Merle Haggard’s guitar licks had more soul than all those flashy guitar solos of Keith Urban.

The weathered rasp of Kris Kristofferson’s voice was more essential than all of Alan Jackson’s slick videos.

Sorry to say this to fans of contemporary country music, but the most meaningful, heartfelt and best country show at the Minnesota State Fair this year was Haggard and Kristofferson on Monday.

Between them, they’ve been living for nearly 160 years and they’ve written almost that many great songs. Haggard alone has 38 No. 1 country hits to his name.

The two members of the Mount Rushmore of country songwriting switched off singing lead on Monday, with Hag’s great group, the Strangers, backing both of them.

When the 79-year-old Kristofferson sang, the 9,341 concertgoers were cheering more so for the songs than the performances. He writes deep, penetrating poetry, often about the dark side of life and relationships. And, even though his voice was far from pretty, he did find his sense of melody on 1971’s “The Pilgrim Chapter 33.”

Although his voice isn’t quite as forceful as it once was, Haggard, 78, definitely had more oomph and clearly riled the Labor Day crowd with “I’ll Just Stay Here and Drink,” “The Fightin’ Side of Me” and, of course, “Okie from Muskogee.” After singing the first line of “Okie,” he stopped and chided the audience to sing with more gusto.

That was one of the few times during the 80-minute set that Hag showed humor, something that had been an essential quality at his duo performances with Kristofferson in 2011 and ’12 in the Twin Cities.

The two pals didn’t really collaborate vocally, not even on “Pancho and Lefty,” the hit duet for Haggard and Willie Nelson. Instead Scott Joss, Haggard’s fiddle player, sang Willie’s part. That tune ranked as one of the Hag highlights. His melancholy guitar work on Kristofferson’s memorable “For the Good Times” made it clear that Hag could help his buddy make it through the night.

The fair couldn’t have picked a more perfect opening act than Sturgill Simpson, 37, who sounded like a cross between Kristofferson and Haggard. His no banter, first-rate set featured about 16 tunes in one hour and a band with a theremin — something you don’t see every day at a country concert.