The Joshua Tree is often considered U2's magnum opus. Released in 1987, it went on to sell over 25 million copies worldwide and launched the rising four piece post-punk outfit into the rock 'n' roll stratosphere. That's the past, and this is now, but the themes of the Irish rock band's Grammy Award winning album aren't dated.

U2: The Joshua Tree Tour with the Lumineers

Recent world events, namely Brexit and the 2016 American presidential election, stirred feelings in the band that mirrored those during the Margaret Thatcher-Ronald Reagan period when Bono and company were writing tracks like "Bullet the Blue Sky," "Red Hill Mining Town" and "Mothers of the Disappeared," says David Howell Evans, better known as The Edge, in Rolling Stonein January.

Joshua Tree songs have "a new meaning and a new resonance today that they didn't have three years ago," The Edge told the magazine.

In honor of The Joshua Tree's 30th anniversary, U2 is touring internationally with an upcoming stop in North Texas at AT&T Stadium in Arlington on May 26.

The band has never revived a legacy album. For better and worse, U2 has frequently reinvented itself, exploring blues, roots-rock, punk, gospel, electronica and folk, always seemingly more interested in pushing into new areas rather than relying on what worked yesteryear.

That's a gutsy philosophy that has both produced occasional missteps and launched the band into unprecedented global popularity. The 2009-2011 U2 360 tour remains the highest-attended and highest-grossing concert tour of all time, Billboard says.

Members of  U2 kick off their world tour of the Joshua Tree in Vancouver, B.C., Friday, May 12, 2017.  (Jonathan Hayward/The Canadian Press via AP)

Members of U2 kick off their world tour of the Joshua Tree in Vancouver, B.C., Friday, May 12, 2017. (Jonathan Hayward/The Canadian Press via AP)

JONATHAN HAYWARD/AP

The Joshua Tree stands out among the band's early catalog as a deepening musical exploration. It is widely considered the band's move toward a more American sound, one inspired by near-constant touring over the better part of the 1980s.

But, the new tour's vintage subject matter hasn't deterred ticket sales. U2: The Joshua Tree 2017 is the most popular act of the summer, outselling second place Ed Sheeran by 65 percent -- "even with less than half the amount of tour dates," according to StubHub.

U2 is known for elaborate stage shows in large stadium settings.  

U2 is known for elaborate stage shows in large stadium settings.  

JONATHAN HAYWARD/AP

It may seem curious that a band founded more than 40 years ago can support the type of elaborate stadium sell outs U2 is known for, especially considering at least 35 percent of ticket purchasers are young -- in the 18 to 34 age range, according to a 2014 Ticketmaster study.

Perhaps that's because practically since their 1980 debut, Boy, U2 has remained at the forefront of popular music, receiving continual airplay and producing studio albums roughly every half decade. Many of U2's older fans may fondly recall pulling the cellophane wrapper off their Joshua Tree cassettes in 1987, but, others likely danced to "Lemon" from 1993's Zooropa at a junior high party or walked across a high school graduation stage to "Beautiful Day" from 2000's All That You Can't Leave Behind.

The Edge on the opening night of U2: The Joshua Tree 2017 in Seattle. 

The Edge on the opening night of U2: The Joshua Tree 2017 in Seattle. 

CHONA KASINGER/NYT

Set lists from the tour's opening shows include other beloved standards from the '80s -- "Bad," "Pride (In the Name of Love)" and "New Year's Day" to name a few -- before launching into The Joshua Tree in full.

But, despite nostalgia and glowing critical reception, that's not to say The Joshua Tree isn't controversial. Reevaluating the album this year, Observer critic Tim Sommer calls it only "half a masterpiece"-- one part great classic rock album. The second, less-popular half, he hears a band on "autopilot."

Therein lies the beauty of the band replaying The Joshua Tree in full in 2017. It reignites the idea of the whole album as one story, where fans are asked to listen from start to finish both in its original context and in modern ones.

Scroll through for more photos from the opening nights of U2: The Joshua Tree 2017:

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