With its stunning musicianship, songwriting and pop artistry, the Beatles’ swan song LP Abbey Road punctuated the end of the band’s career in fine style. Released 50 years ago Thursday, Abbey Road will be rightly celebrated for its crowning place in the group’s creative pantheon.

But Abbey Road also marked the culmination of a demographic explosion like nothing else in the history of the arts. Their near-universal appeal by the time Abbey Road was released helps us to understand how their popularity grew so precipitously and why they still matter.

Ground zero for American Beatlemania occurred on Feb. 9, 1964, with the band’s bravura appearance on The Ed Sullivan Show. On that night, the Beatles enjoyed a television audience of more than 73 million viewers, which was roughly 40% of the U.S. population during that era.

But when it came to buying their records and merch, sales figures show that the group’s trailblazing success was largely due to just one fraction of that group: the much-ballyhooed 12-24 demographic, predominantly made of young female fans or “teenyboppers.” Americans in that age range had the leisure time to pursue their passions with great zeal and, for many teenaged fans, ready access to their parents’ disposable income.

In those early years, the Beatles were a teenybopper phenomenon, yet another example of that era’s generation gap. The cultural difference between the Baby Boomers, who couldn’t get enough of the Beatles, and their Depression-baby parents was staggering. And it might have continued in that direction if the Fab Four had never moved beyond the beat-band sound of such early records as “She Loves You,” “I Want to Hold Your Hand,” “Can’t Buy Me Love,” “A Hard Day’s Night” and “Eight Days a Week.”

But with “Yesterday,” recorded in June 1965, the Beatles changed everything. Encouraged by their classically trained producer George Martin, the group consented to the inclusion of a string quartet to accompany Paul McCartney’s poignant ballad about lost love. Not only did “Yesterday” emerge as a chart-topping American hit, but the groundbreaking song also saw the band growing their demographic to include the highly desirable world of working adults, ages 25-54, who longed for something more sophisticated.

From that point forward, Martin and the Beatles gave it to them — and that fall, the band expanded their musical repertoire even further, with songs like McCartney’s easy-listening “Michelle” or John Lennon’s “Norwegian Wood (This Bird Has Flown),” with its adult-oriented themes.

Even more remarkably, by the following year the Beatles had charted new demographic terrain. Released in August 1966, the “Yellow Submarine”/“Eleanor Rigby” single saw the band topping the charts yet again. With one fell swoop, they managed to add two more demographics to their audience. With its good-natured storyline and nautical sound effects, “Yellow Submarine” drew children and pre-teens into the Beatles’ camp, while “Eleanor Rigby” attracted the post-55 demographic in droves.

Quite suddenly, the Beatles dominated every quadrant of the consumer age range.

As they consolidated their popularity, folks beyond the teenybopper set began to give their early work a second listen. By 1967, with the releases of the “Penny Lane”/“Strawberry Fields Forever” single and the Sgt. Pepper’s Lonely Hearts Club Band album, there weren’t any chinks in the band’s demographic armor.

Musician Adrian Belew later recalled that unexpected thrill of observing when “‘Strawberry Fields Forever’ was being broadcast and thousands of housewives were listening to this bizarre piece of music.” And it was no less than composer Leonard Bernstein who proclaimed the achievement of Sgt. Pepper’s apocalyptic closing song “A Day in the Life” and its capacity to “sustain me, rejuvenate me, inflame my senses and sensibilities.”

With the release of Abbey Road in the autumn months of 1969, the Beatles’ unmatched market penetration served them well. If anything, the album succeeded in enlarging their fan base yet again. With Martin’s orchestration on full display, Abbey Road was a genuine crowd-pleaser and the Beatles’ demographic power reached its zenith.

And that was when the band called it quits. Though Let It Be came out after, they never recorded another album together. Had they broken up earlier, or even later, they might have been remembered as a band that made music for some individual generation. Rather, with Abbey Road they went out as a band to which everyone listened. The album created an enduring sense of mystique surrounding their achievement. And with each new generation, the Beatles have managed to grow their reach even further.

This demographic range has persisted into the present day. When the band took the 1960s by storm, their music and lyrics were “so fluid and intelligent,” music historian Greil Marcus has observed, “that for years they made nearly everything else on the radio sound faintly stupid.”

Apparently, things haven’t changed in the slightest. In a 2016 Billboard magazine study of the Beatles’ performance on Spotify—a streaming service where more than 79% of users were born after the Beatles’ disbandment—the group continued to reign supreme across all demographics, generating an awe-inspiring 250 million streams per month and outperforming the rest of the industry in the process.

Historians’ perspectives on how the past informs the present

Kenneth Womack is the author of a two-volume biography of the life and work of Beatles producer George Martin. Womack is Dean of the Wayne D. McMurray School of Humanities and Social Sciences at Monmouth University. His latest book is Solid State: The Story of Abbey Road and the End of the Beatles. You can learn more about his work at kennethwomack.com.

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