When the Byrds kicked off the second phase of their multistage career in March 1966 with the release of "Eight Miles High," they also happened to launch a new chapter in rock history.

The quintet pretty much spent the previous year mining the Bob Dylan songbook, fine-tuning its own collective songwriting talents and perfecting the folk-rock genre with chart-topping singles like "Mr. Tambourine Man" and "Turn! Turn! Turn!" But as their busy 1965 - which included two albums and many live appearances - started to wind down, the Byrds were getting restless.

That fall, the band participated in a tour spearheaded by American Bandstand host Dick Clark. They traveled city to city by bus and kept themselves occupied by listening to music. One day, a friend of David Crosby's played jazz great John Coltrane's 1961 album Africa/Brass, which incorporated Afro-Indian improvisations into a more traditional big-band setting.

The music "seared through the center of my chest like a white-hot poker," noted Roger McGuinn - who, like Crosby, was one of the Byrds' three singers, songwriters and guitarists - in 2006's There Is a Season box set. He recorded the album with a portable cassette deck he recently picked up, filling the other side of the tape with Indian ragas by Ravi Shankar. The band listened to the tape nonstop for the rest of the tour.

When they entered RCA Studios in Los Angeles for a session in late December, they had an idea for a new song inspired by their recent obsession. A first take of "Eight Miles High" - preferred by the group's members - was rejected by the Byrds' record company because it wasn't recorded in one of its studios. So, the band returned to an approved studio a few weeks later on Jan. 25, 1966, and completed the version that was released as a single on March 14.

From the start, the Byrds knew they were getting into something new and significant with "Eight Miles High." In early 1966, there still wasn't much that sounded like it. Even the Beatles, the most forward-thinking band of the era, had just unveiled their first real exploration of Indian music with "Norwegian Wood (This Bird Has Flown)" from Rubber Soul, which came out in December. That classic song's key sitar line was inspired by Shankar, whose music the Byrds were immersed in during their recent tour.

Listen to the Byrds' 'Eight Miles High'

But they took it even further in "Eight Miles High," capping it with a head-spinning guitar solo based on a jazz progression inspired by Coltrane. McGuinn explained in There Is a Season that his solo "wasn't mapped out"; instead, he had a "basic skeleton" borrowed from a four-note Africa/Brass riff he then improvised on.

Lyrically, the song nodded to the band's road adventures, too - specifically an August trip to London and the subsequent English tour. Gene Clark - another of the Byrds' singers, songwriters and guitarists - wrote a poem that was later expanded into song form with assist from Crosby and McGuinn. They collaborated on the music, with suggestions tossed around among them, before settling on the finished piece, which was highlighted by McGuinn's skyscraping 12-string solo.

But they hit a snag as the song was making its way up the charts. An industry newsletter sent to radio stations claimed "Eight Miles High" was about drugs, which resulted in the song being banned in some markets. While band members denied the allegation at the time, they eventually admitted that the track was indeed a drug song. "We were [even] stoned when we wrote it," Crosby said in the 1998 book The Byrds: Timeless Flight Revisited.

Still, it wasn't so much the song's subtext as its unconventional structure that abetted "Eight Miles High"'s struggle on the charts: Not only was its three-and-a-half-minute running time considerably longer than most radio singles in 1966, there weren't a whole lot of pop songs grabbing inspiration from John Coltrane and Ravi Shankar back then either. It was simply ahead of its time, even for the psychedelic genre it helped spawn; wthin a year or so, it wouldn't sound so foreign. Still, "Eight Miles High" managed to make it to No. 14 that spring.

Less than two weeks before the single was released, Clark left the band. The cowriter of "Eight Miles High" had a fear of flying and walked off a plane that was headed to New York to start yet another tour. He never came back. Clark later attributed his departure to a "nervous breakdown"; as he's quoted in the biography Mr. Tambourine Man, "Finally, I just had had it."

"Eight Miles High" ended up as the Side Two opener on the Byrds' third album, Fifth Dimension, which was released in July. The LP marked a shift in the band's direction and sound; it wouldn't be the last time. They got further into psychedelia on Younger Than Yesterday from early 1967. By the time The Notorious Byrd Brothers came out in January 1968, Crosby was gone (though he does appear on a number of the album's tracks), and they were incorporating everything from jazz to country to electronic noise into their music.

Before the '60s were over, they'd make a total move into country, with McGuinn the only member left from the original quintet as they entered the next decade.

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