Before she launched her acting career with "Grease," Olivia Newton-John was best-known for her genre-bending music. The singer straddled the line between country and pop, and in 1975 released "Please Mr. Please," which peaked at #3 on the Billboard Hot 100 and #5 on the Hot Country Songs chart.

An artist named Peter Sterling Radcliffe wrote a country song called "You're My First, You're My Last, My In-Between" but it wasn't recorded for 21 years. His friend Barry White put a disco twist on the song and released it in 1974. His version, "You're the First, the Last, My Everything" peaked at #2 on the Billboard 100 chart and was certified Gold by the Recording Industry Association of America on Dec. 18, 1974.

When Sammy Johns first wrote "Chevy Van" it was shelved for nearly two years. The suggestive song about a one-night stand in the back of a van was finally released in 1975 and took the charts by storm, reaching #5 on the Billboard Hot 100.

"When Will I Be Loved" was originally written and recorded by Phil Everly in 1960. His version was a hit, but when Linda Ronstadt released her own version of the song in 1975, it soared to #1 on the Billboard Hot Country Songs chart.

Brazilian singer-songwriter Morris Albert penned an international hit in 1974 with his soft rock ballad "Feelings." The single ended up being the title track of his 1975 debut album, which was the most successful of his career.

"Fallin' in Love" is the title track of Hamilton, Joe Frank & Reynolds' third and final album and the trio's only chart-topping hit. Oddly enough, Tommy Reynolds left the group in 1972, but the band decided not to change its name after replacing him with Alan Dennison.

Billy Swan found tremendous crossover success with the title track to his 1974 debut album "I Can Help." The single topped both the Billboard Hot 100 and Hot Country Songs in the U.S.; however, the rockabilly musician was unable to pen another hit.

10cc was already enjoying success in the U.K. when it released "I'm Not in Love." The single broke the art-rockers into the U.S. market and peaked at #2 on the charts.

There were numerous setbacks for Wings, Paul McCartney's first post-Beatles musical endeavor, but after the 1973 release of the group's third album, "Band on the Run," momentum held and Wings finally landed the chart-topping single "Listen to What the Man Said" from its fourth album "Venus and Mars" in 1975. That led to a world tour and continued success for the then-solidified group.

Jessi Colter is famous for being part of the outlaw country movement, but her biggest hit "I'm Not Lisa" teeters toward pop. The single, which was produced by her husband Waylon Jennings, topped the country chart and peaked at #4 on Billboard's Hot 100 chart.

Michael Martin Murphey was a relatively unknown artist before releasing his Top 10 hit "Wildfire." The country classic is shrouded in mystery and Murphey claims to have dreamed up the strange story that inspired the song.

"Cat's in the Cradle" tells the heart-wrenching tale of a father who doesn't try to make time for his son until it's too late. The folk-rock song struck a chord upon its release in 1974 and earned Harry Chapin his first and only #1 single.

Barry Manilow first wrote "Could It Be Magic" in 1971 as an uptempo song with his studio band Featherbed with Barry Manilow. The popular ballad version was then released on the singer's eponymous debut album two years later, but it wasn't until it was re-released in 1975 that the hit broke the Top 10, peaking at #6 on the Billboard Hot 100 chart.

"Have You Never Been Mellow" marked Olivia Newton-John's second chart-topping single. The soft-rock hit also scored the singer-actor a Grammy nomination for best pop vocal performance.

"Mandy" is considered the song that launched Barry Manilow into superstardom, but many fans don't realize that it's actually a cover. The song, which was originally called "Brandy," was already a hit in the U.K. when its original writer Scott English released it in 1971.

Elton John knew he had to cover "Lucy in the Sky with Diamonds" when he saw The Beatles' 1968 film "Yellow Submarine," which features the timeless song. When he finally did in 1974, John was able to recruit the song's writer, John Lennon, to contribute backing vocals and guitar on his version under the pseudonym Dr. Winston O'Boogie.

Gerry Beckley wrote "Sister Golden Hair" more than a year before his band America recorded the song. It was ready to go for its 1974 album "Holiday," but got cut. It ended up being the lead single on America's 1975 album "Hearts" and quickly became the folk rockers' second #1 single.

When The Marvelettes released "Please Mr. Postman" in 1961, it made history by becoming the first Motown Records song to top the pop charts. Thirteen years later, The Carpenters put its spin on the single and reinvigorated it into another #1 hit.

"Magic" was Pilot's first and only hit; however, 50 years after its release the melody is as popular as ever thanks to a type 2 diabetes drug commercial. Ozempic's jingle "Oh, oh, oh, Ozempic!" is a play on the song's catchy chorus, "Oh, oh, oh, it's magic."

Ohio Players ruled the R&B charts in the '70s, and the funk-soul outfit celebrated its largest crossover success in 1975 with "Fire." The single, which had already hit #1 on the R&B chart, topped the Billboard Hot 100 chart, too.

"Jackie Blue" is a song about a reclusive girl, but The Ozark Mountain Daredevils biggest hit was originally written about a male drug dealer. When the track was brought to the band's label A&M, it insisted that Jackie needed to be a girl, so lyricist Steve Cash and drummer Larry Lee changed the lyrics.

The Isley Brothers were hitmakers in the '60s, releasing classics like "Twist and Shout" and "It's Your Thing," but the '70s saw an evolution to their sound. "Fight the Power" is a rebellious anthem that's funky beat broke it into the top five on the pop chart.

Helen Reddy recorded three #1 hits, and they all came out in the '70s. The quiet, fantastical single "Angie Baby" was her third and final chart-topper.

Freddy Fender originally recorded "Wasted Days and Wasted Nights" in 1959 but served prison time for a drug charge the following year. In 1975, he recorded a new version of the song and it broke the top 10 on the Billboard Hot 100 chart.

"Boogie On Reggae Woman" peaked at #3 on the Billboard Hot 100 chart and won a Grammy for Best R&B Vocal. The standout single is featured on Stevie Wonder's 1974 album "Fulfillingness' First Finale," which was his first LP after almost dying in a car accident the year before.

Major Harris began his career as a member of the Delfonics but left the group in 1974 to pursue a solo career. The move proved to be a good one when he released his hit single "Love Won't Let Me Wait" the following year.

"Why Can't We Be Friends?" is the title track off War's fifth studio album. It peaked at #6 on the Billboard Hot 100 chart and NASA famously transmitted it to the Apollo-Soyuz Space mission in 1975.

Labelle's racy hit about New Orleans sex workers soared to the top of the Billboard Hot 100 chart in 1975. In 2001, the song topped the chart once again when Pink, Mya, Lil Kim, and Christina Aguilera covered it for the "Moulin Rouge!" soundtrack.

The hustle was a signature dance move of the disco era, and Van McCoy's eponymous 1975 hit was one of the most memorable songs of the '70s. Not only did "The Hustle" top the Billboard Hot 100 chart, but it won the Grammy for Best Pop Instrumental Performance, too.

The Average White Band lived up to its name—the group hailed from Scotland and all the members were white—but they could lay down a groove. Despite being a mostly instrumental track, "Pick Up the Pieces" was a funky hit that topped the Billboard Hot 100 chart in early 1975.

Janis Ian had seen success before releasing her 1975 album "Between the Lines," but that project and its single "At Seventeen" proved to be the largest hit of her career. The timeless song, which explores the traumas of youth, is heralded for its honest perspective on life as a teenager.

Jerry Butler released his hit song "He Will Break Your Heart" in 1960. Fifteen years later, Tony Orlando and Dawn covered the track and their version ended up being a chart-topper.

B.J. Thomas' forlorn ballad "(Hey Won't You Play) Another Somebody Done Somebody Wrong Song" was a crossover hit for the country star. The song topped the pop chart and also won a Grammy for Best Country Song in 1975.

Ironically enough, Sweet's glam rock hit "The Ballroom Blitz" was inspired by a gig where the audience was so disappointed with the band that they drove them offstage by throwing objects at them. The band got the last laugh when the song peaked at #5 on the Billboard Hot 100 chart and became truly iconic thanks to a memorable cover in the 1992 movie "Wayne's World."

"Black Water" was one of two chart-topping hits in The Doobie Brothers' career, and if it wasn't for a serendipitous noodling session it may have never been written. The band's producer Ted Templeman overheard guitarist Patrick Simmons playing around with the riff and encouraged him to write a song around it.

Carl Douglas is considered a one-hit wonder but that hit is a memorable one. "Kung Fu Fighting" is one of the most iconic disco tracks from the '70s and is also a great homage to the martial arts film craze of the same era.

Minnie Riperton's "Lovin' You" was a chart-topping hit, and so much more. The singer, who happens to be actor Maya Rudolph's mother, wrote the dreamy song with her husband Richard Rudolph as a lullaby for their children.

All five of the Eagles' chart-topping hits came in the '70s, starting with 1974's "Best of My Love." According to singer Don Henley, most of the song's lyrics were written in a booth at the Los Angeles restaurant Dan Tana's.

The Bee Gees had a heyday in the '70s, recording nine chart-topping singles; however, when they released "Jive Talkin,'" it was their first #1 hit since 1971's "How to Mend a Broken Heart." The song was originally titled "Drive Talkin'" but was changed after Barry Gibb accidentally sang "Ji-ji-jive talkin'" in the studio.

After finding immense success with his first country crossover "Take Me Home, Country Roads" in 1971, John Denver struck gold again four years later with "Thank God I'm a Country Boy." The song was actually written by John Martin Sommers—a multi-instrumentalist in Denver's backing band—and the singer-songwriter decided to record the track himself after hearing Sommers perform it in a club.

1975 was quite the year for The Eagles. Five months after recording its first #1 hit, "Best of My Love," the band released another chart-topper with "One of These Nights." The song is featured on its hit album of the same name, which has since gone 4x platinum.

Neil Sedaka penned six top 10 hits from the late-'50s through the mid-'60s, then hit a dry spell on the U.S. charts. "Laughter in the Rain" is considered the singer-songwriter and pianist's American comeback and marked his first chart-topping hit since 1962's "Breaking Up Is Hard to Do."

What started out as a riff of The Flares' 1961 song "Foot Stomping" with John Lennon and guitarist Carlos Alomar resulted in David Bowie's first #1 hit, "Fame." Bowie famously sang the "Young Americans" single on "Soul Train," becoming one of the first white artists to perform on the show.

Earth, Wind & Fire is one of the most iconic bands to come out of the soul, funk and disco scene. Although it penned seven top 10 singles through the mid-'70s and early-'80s, "Shining Star" is the group's only #1 hit.

When Grand Funk Railroad was traveling the country, drummer Don Brewer loved starting sing-alongs to the 1967 song "Some Kind of Wonderful" by the Soul Brothers Six. The band's manager suggested they record it, and the cover became one of their biggest hits.

Although "My Eyes Adored You" is credited to Frankie Valli, the song also features his Four Seasons bandmates. After finding tremendous success in the early- and mid-'60s, the group hadn't recorded a Top 40 hit since 1967. The chart-topping ballad about unrequited love revived Valli's career and paved the way for a group comeback in 1976.

"Before the Next Teardrop Falls" was originally recorded in 1967 by Duane Dee and covered by a number of artists before Freddy Fender released his version of it in 1974. The Tejano singer was hesitant to record a country song but his producer Huey Meaux convinced him to do it. The decision was a good one—Fender's rendition ended up topping both the country and pop charts.

After releasing his version of "Lucy in the Sky with Diamonds," Elton John decided to record another stand-alone single called "Philadelphia Freedom." Like the Beatles cover, this album-less track soared to the top of the Billboard Hot 100 chart. It was later featured on 1977's "Elton John's Greatest Hits Volume 2."

Glen Campbell had been climbing the pop charts for 14 years before releasing his first chart-topping hit on the Billboard Hot 100. "Rhinestone Cowboy," which was originally recorded by Larry Weiss in 1974, also hit #1 on the country charts. It was the first single to top both charts simultaneously since 1961.

Neil Sedaka, who co-wrote "Love Will Keep Us Together" with Howard Greenfield, was the first to record the song, but it was Captain & Tennille that made it a hit. Toni Tennille loved the track, and she and her husband decided to release a cover as their first major-label single. Their version ascended to the top of the Billboard Hot 100 chart and ended up being the title track of Captain & Tennille's debut album.

Additional research by Wade Zhou. Story editing by Cynthia Rebolledo. Copy editing by Lois Hince.