Is This the Most Played Song in Music History?

Nobody famous sang this tune. It was never a hit single and got almost no play on Top 40 radio. There’s even a dispute over the exact title. Yet “It’s a Small World,” also known as “It’s a Small, Small World” and “It’s a Small World (After All),” is very likely the most played song in music history — nearly 50 million times. And it was first heard 50 years ago this month.

Various sources cite the Righteous Brothers’ “You’ve Lost That Lovin’ Feelin'” (1964) as having more than eight million plays on radio and TV, and The Beatles’ “Yesterday” (1965) with at least seven million in the U.S. alone, and many more in the rest of the world. Irving Berlin’s “White Christmas,” introduced by Bing Crosby in 1942, has inundated the airwaves ever since, but for only a few weeks each year. There’s little debate that Patty and Mildred Hill’s “Happy Birthday to You” (originally “Good Morning to You”) has been performed more than any other song, but not in public; if you do, and don’t pay royalties, the possessive copyright holders at Warner/Chappell Music will sue your pants off — and take all your birthday gifts, too.

That leaves “It’s a Small World,” composed by Disney staff writers Richard and Robert Sherman for the 1964-65 New York World’s Fair pavilion ride officially known as “PEPSI Present’s Walt Disney’s ‘It’s a Small World’ — a Salute to UNICEF and the World’s Children.” In his authoritative 1998 book Songwriters: A Biographical Dictionary with Discography, Nigel Harrison proclaims the song “the most performed composition in the world.” Richard Sherman, the surviving brother, thinks so too.

(READ: Stephen M. Silverman’s tribute to “It’s a Small World”)

And how did we arrive at the 50-million number? We’ll get to the math later.

On April 22, 1964, when the World’s Fair opened in Flushing Meadows, Queens, the star attraction was Disney’s UNICEF pavilion. Designed by Disney “Imagineer” Mary Blair, the “small world” ride took passengers on an 11-minute boat tour through a series of halls representing different parts of the world, as several hundred “animatronic” (mechanical) dolls cavorted to the children’s chorus of the Shermans’ simple refrain, over and over and over. After two six-month seasons in New York, the ride was installed at Disneyland in Anaheim. As the company opened new parks — Florida’s Walt Disney World in 1971, Tokyo Disneyland in 1983, Paris in 1992 and Hong Kong in 2008 — “it’s a small world” replicated like kudzu, and its signature song latched or leeched its way into tens of millions of minds.

If you’ve never been to a Disney theme park, you may not have heard “It’s a Small World.” If you have, no operation short of a lobotomy will extract it from your memory. A four-chord jingle selling international brotherhood, it begins with this verse: “It’s a world of laughter / A world of tears / It’s a world of hopes / And a world of fears / There’s so much that we share / That it’s time we’re aware / It’s a small world after all.” And then there’s that insistent, infernally unforgettable chorus: “It’s a small world after all / It’s a small world after all / It’s a small world after all / It’s a small, small world.”

(READ: The entrepreneurial genius of Walt Disney)

Disney was all over the 1964-65 World’s Fair, having created the Carousel of Progress for General Electric, an animatronic Abe Lincoln for the Illinois pavilion and an early form of the PeopleMover, an elevated train ride, for the Ford Motor Company. Pepsi had dithered over its attraction so long that Disney had less than a year to prepare this attraction. According to one anecdote, movie star Joan Crawford brought Walt Disney together with her husband, Pepsi CEO Alfred Steele, to get the project launched.

Robert Sherman (born 1925, died 2012 at 86) and Richard (born 1928 and still around at 85) were the sons of songwriter Al Sherman, who composed novelty tunes for the Depression era, including the Eddie Cantor favorite “(Potatoes Are Cheaper, Tomatoes Are Cheaper) Now’s the Time to Fall in Love.” Al’s “She So Unusual” was a 1929 hit for Helen Kane and covered by Cyndi Lauper in 1983; his “You Gotta Be a Football Hero” served as a fight song in countless college stadiums. Robert and Richard took up Dad’s trade and were soon working for Disney. They composed late-’50s hits for (“Let’s Get Together,” “Tall Paul”) for Mousketeer Annette Funicello, and they provided the studio with an Oscar-winning score for Mary Poppins. The brothers’ biggest non-Disney hits: the top-of-the-pops “You’re Sixteen” for Johnny Burnette in 1960 and the songs for the 1967 movie Chitty Chitty Bang Bang.

(READ: our 1964 review of Mary Poppins by subscribing to TIME)

In the original “small world” concept, dolls sang different national anthems in different halls, but that resulted in what Richard Sherman recalled as “cacophony.” With the 1962 Cuban Missile Crisis haunting them, the Shermans composed their Cold War peace anthem: a prayer to find “so much that we share” in “a world of fears.” As the ride opened in Disney parks outside the U.S., the song added choruses performed in French (Paris), Japanese (Tokyo) and Cantonese, Korean, Putonghua and Tagalog (Hong Kong). Universal brotherhood may be as imperiled now as it was in 1964, but the song composed by the Sherman brothers has gone totally global. And here’s a guess: Because they were contract writers for Disney, the Shermans got no royalties for the song.

Now the math. The “it’s a small world” ride has run in the five Disney parks for a total of 149 years and eight months. Shave off a few years for times when the parks are closed or the ride is shut down (as when the Anaheim park prepares its Christmas redecoration of “small world”), and add the 12 months when the ride was in New York, we get 148 years. Multiply by 365 days per year and you get 54,020 days. According to a Disney fact sheet, “During a 16-hour operating day in the parks, the ‘It’s a Small World’ song is played, on average, 1,200 times.” That would bring the total plays at Disney parks to 64,820,000. Ah, but many of the parks aren’t open 16 hours a day, especially in the winter. The rough, year-round average is about 12 hours. So we take three quarters of the 64-million number and get a very conservative 48,618,000 times the song has been played. Round that up to “nearly 50 million.”

(READ: “If Heaven Ain’t a Lot Like Disney”)

More millions, in plays and dollars, are to come. Last week Disney announced a movie version of the attraction, to be directed by Jon Turteltaub (National Treasure) and written by Jared Stern (who contributed to Disney’s animated features Bolt, The Princess and the Frog and Wreck-It Ralph). Wait a minute: a live-action film from a theme-park ride that has no plot, no identifiable characters and one endlessly repeated song? It sounds crazy — unless you’re aware of the four Disney features based on its Pirates of the Caribbean ride. They yo-ho-hoed to a nifty $3.7 billion at the worldwide box office.

(FIND: The first Pirates of the Caribbean movie on TIME’s Top 10 of 2003)

Now the studio is banking a world of hope that “small world” will be a similarly rich movie franchise. If that comes to pass, we may never get the most played song in music history out of our heads.