B.J. Thomas knows he wasn’t Burt Bacharach’s first choice. Though it’s Thomas’s voice, scratchy from laryngitis, that sings “Raindrops Keep Fallin’ on My Head” over the classic bicycle sequence in Butch Cassidy and the Sundance Kid, composer Bacharach initially brought the song to Ray Stevens, best known at the time for such novelty hits as “Along Came Jones” and “Gitarzan.” Stevens passed, and his loss was Thomas’s gain. “I don’t know why anyone would pass on a song that’s going to be in a Paul Newman movie,” Thomas said in a recent interview. “I don’t get it.”

Stevens was far from the last person who didn’t quite get “Raindrops Keep Fallin’ on My Head”—or Butch Cassidy and the Sundance Kid, for that matter. When it premiered 50 years ago this week, George Roy Hill’s revisionist Western initially struggled with critics. But thanks to its charismatic leads—Paul Newman and Robert Redford as “two-bit outlaws on the dodge”—William Goldman’s puckish, Oscar-winning script, and, especially, Bacharach’s unconventional score, the film went on to be the biggest box office hit of 1969 and has since been embraced as a classic.

Composed by Burt Bacharach and lyricist Hal David, “Raindrops” is the film’s breakout hit and its legacy song; an upbeat and indefatigable ode to feeling free. It remains an irresistible earworm and perfectly suited to a film that was made for its rebellious, radical times and went against the traditional Western grain.

Here was a Western in which Butch, the leader of the Hole-in-the-Wall Gang, sucker-kicked a challenger to his leadership in the groin. You didn’t see John Wayne’s lawman Rooster Cogburn kicking Robert Duvall’s Ned Pepper in the balls during their climactic showdown in the old-school Western True Grit, which was released the same year.

But perhaps the most radical element of Butch Cassidy was Burt Bacharach’s score. Bacharach was an audacious but deliberate choice by George Roy Hill, who, fun fact, had used Elmer Bernstein, composer of the classic Western score for The Magnificent Seven, for his previous three films. Bacharach had scored three comedies prior to Butch, but with Hal David, he was better known as the co-hitmaker behind stylish and sophisticated songs for Dionne Warwick: “I Say a Little Prayer,” “Do You Know the Way to San Jose,” and “I’ll Never Fall in Love Again.”

Just as the movie upended its genre, Bacharach’s music for Butch Cassidy subverted audience expectations of what a Western score should sound like. Check out “South American Getaway,” which accompanies the film’s chase scene—no epic sweep of How the West Was Won or iconic heroism of Magnificent Seven here.

“The picture was designed for a contemporary feel,” Hill, a Yale music major, said in a documentary about Butch Cassidy filmed in 1968-69. “The characters are modern rather than traditional in approach and temperament, and [Goldman’s] dialogue…has a very contemporary rhythm and sound to it, and we didn’t want a traditional Western score.”

It was a controversial creative choice. “There are only seven music sequences in the entire film,” said film-music expert Jon Burlingame. Hill did not want music playing under the dialogue, which means the soundtrack runs less than a half hour. And that brings us to “Raindrops Keep Fallin’ on My Head,” which arrives about 30 minutes into the film while the goings are still loose and affable. The bicycle scene was shot as a playful musical interlude. To give Bacharach an idea of what he was looking for musically, Hill had cut the sequence to Simon & Garfunkel’s jaunty “The Fifty-Ninth Street Bridge Song (Feelin’ Groovy).”

Watching the scene on a moviola, Bacharach knew the song would start with a ukulele, he wrote in his autobiography, Anyone Who Had a Heart. “I wrote the entire melody, and the only words that kept running through my mind from top to bottom were ‘Raindrops keep fallin’ on my head,’” he recalled. David tried to come up with another title, as the sun is shining brightly throughout the sequence.

The 20th Century Fox board, Bacharach wrote, was against the song. It considered it “too risky and unconventional.” But the song worked much in the way that the out-of-period Scott Joplin rags worked in Hill’s film The Sting, which also won an Academy Award for its score.

“I’m in the minority,” Thomas, who was fresh off his hit “Hooked on a Feeling” at the time, told Vanity Fair. “I think the song made sense [in the film]. ‘Raindrops’ is an American song. The song came from Butch, and it says as long as you’re free, you’re okay. It worked for me.”

When Thomas performed the vocal for the film’s soundtrack, he was recovering from an acute case of laryngitis. “We got through five takes; I couldn’t have done one more,” he said with a laugh. “I thought I sounded terrible, scratchy. As it turned out, Mr. Bacharach liked that sound. He thought it sounded more authentic.”

The Butch Cassidy soundtrack was among A&M Records’ best-selling albums that year. In an email to Vanity Fair, Herb Alpert, the label’s cofounder, said, “In the movie you didn’t know how these two likable bandits would end up and Burt Bacharach’s unusual and creative music had the same flavor, and then out of the blue comes ‘Raindrops Keep Falling on My Head.’ Now, that’s art.”

A single version of “Raindrops” was released in October 1969. “The studio didn’t realize how it would connect with the public and it became a huge hit almost overnight,” Burlingame said. The song went to No. 1 on the Billboard Hot 100 chart and stayed there for four weeks. It went on to win the Academy Award for best original song (Bacharach won a second Oscar for the film’s score).

“Raindrops” has served as a go-to pop-culture reference ever since, turning up, for example, in Monty Python’s Flying Circus, The Simpsons, Arrested Development, and on the Forrest Gump and Spider-Man 2 soundtracks.

As it turns out, Stevens didn’t actually hate “Raindrops,” as Bacharach claimed in his memoir. It was simply a case of bad judgment. “I was very flattered to be asked because Burt Bacharach and Hal David are two of the greatest songwriters to come down the road,” Stevens said in a phone interview. “I flew to L.A. and I went to Burt’s house, and he played it for me. I had just spent weeks in the studio recording a Kris Kristofferson song, ‘Sunday Morning Coming Down,’ and I was so invested in that, I knew if I postponed it [to work on ‘Raindrops’], somebody else would beat me out on the Kristofferson song. My song was not a hit. In hindsight I’m thinking my public image wasn’t conducive to me singing a song about being stoned on a Sunday morning. Johnny Cash came out with it a year later and it was a hit. My image didn’t sell ‘Sunday Morning’ and his did.”

Stevens did see Butch Cassidy, though, and loved it. “B.J. Thomas did a terrific job,” he said.

After “Sunday Morning Coming Down” failed to take off, Stevens wrote and recorded “Everything Is Beautiful,” which earned him a Grammy and became his theme song when he hosted Andy Williams’s summer replacement TV variety series. Stevens said he actually sings “Raindrops” in concert at his Nashville-based theater, Ray Stevens CabaRay Showroom, “every now and then.” He is going to be inducted into the Country Music Hall of Fame in October.

“Raindrops” is Thomas’s biggest hit to date and is still his favorite to sing. “It’s been a very meaningful song to a lot of people,” he said.

He maintains that it never gets old. “Man, never,” he emphasized. “A lot of my [musician] friends say they get tired of this song or sick of that song. I have never felt that way. I’ve got lifetime memories tied to my songs; I never get tired of singing them. I don’t blame you if you don’t believe me, but I’ve never had that problem.”

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