By that point, 21's run was beginning to verge on the historic. The album spent 13 weeks total atop the Billboard 200 in 2011, and then returned to the top spot for 10 of the first 11 weeks of 2012 -- boosted by a Grammys victory lap in which Adele took home six combined trophies, including song and record of the year for "Deep" and album of the year for 21 -- to become easily the longest-reigning No. 1 album of the 21st century. That February, Adele mania was so strong that even debut album 19 returned to a new peak on the chart, reaching No. 4 after getting no higher than No. 10 during its original run. And by the end of 2012, 21 accomplished something many industry prognosticators thought impossible for a new album in the 2010s: It was certified Diamond by the RIAA for shipments of over 10 million copies, the first album released since Usher's Confessions in 2004 to notch such an achievement.
How did 21 do it? Well, if you listened to the traditionalists at the time, she did it by bringing "real music" back -- the kind of live instrument-based, feeling-first, soulful pop music that listeners weren't getting from a radio market increasingly saturated with Max Martin and Dr. Luke's brand of heavily compressed, synth-soaked, aggressively catchy turbo-pop. But while Adele's music did have a feeling of timelessness -- mostly meaning it just didn't sound unmistakably like the specific moment in time it came from -- it wasn't from a different mainstream galaxy, either. In its own way, "Rolling in the Deep" sounded as punchy on the radio in 2011 as "Firework" or "We R Who We R," while "Someone Like You" was of a piece with the piano balladry of Bruno Mars or OneRepublic (whose Ryan Tedder even produced and co-wrote fourth 21 single, "Rumour Has It"). The set snowballed commercially because it could speak to everyone in the family minivan -- the kids listening to Top 40, the parents reared on Motown and classic rock, maybe even the grandparents longing for the days of crooners on the radio.
But mostly, Adele worked because of Adele. She was a unique presence not only in 2011, but in all of 21st century pop: a preternaturally gifted singer and songwriter with a leave-it-all-on-the-floor approach to recording and performing -- and also an earthy, relatable, and strangely unassuming personality both on and off the stage. Even as Adele rose to a strata of sales that not even Lady Gaga or Beyoncé could claim, she never seemed like she was becoming part of the pop machine: She felt fresh, sincere, unworked. Due to the combination of her peerless instrument and her unquestioned personal and artistic integrity, Adele's heartbreak anthems connected on a wavelength entirely of their own, as if no one had ever quite meant it like her before. It was an unrepeatable formula, because the mere act of trying to repeat the formula would muck up the essential charm of the whole thing.
Thanks in large part to the assistance of Adele and the 5.8 million copies moved by 21, album sales in the music industry actually improved 1% in 2011 -- the first year where the numbers went up since 2004. Digital song sales saw even more robust improvement, raising 8.5% to a then-record 1.27 billion downloads. While most execs approached the evidence of music industry growth with caution --“It’s encouraging... but we’d be silly to jump up and down,” said Rob Stringer, then-chairman of Columbia, Adele's American distribution label, in a New York Times year-end recap -- others wondered if maybe there was finally a light at the end of the tunnel for the long-suffering music biz. “I think it’s the sign that the music industry is finally starting to come to figure out the digital present and future, at least when it comes to download sales," Gartner media analyst Michael McGuire said in the same Times article. "Perhaps we’ve seen the bottom.”
Such optimism would prove largely unfounded over the next few years. Album sales dropped 4% in 2012, a period in which 21 was again the year's best performer with 4.41 million copies sold -- the first time in the SoundScan era that an album had been the overall best-seller two years in a row. Album sales took an 8% tumble in 2013, and perhaps more alarmingly, digital song sales also dipped 6%, their first overall decrease over a full year since SoundScan began tracking them in 2003. The slippage got steeper in 2014, when album sales and digital song sales fell 11% and 14%, respectively. While blockbuster albums were released by major stars over this period -- Taylor Swift's crossover-completing 1989, Justin Timberlake's long-awaited comeback LP The 20/20 Experience, Beyoncé's game-changing, surprise-dropped self-titled set -- none of them even approached 21's stratospheric sales figures, leaving industry experts to wonder if any artist would be able to match that album's anomalous performance again.