Mariah Carey. Boyz II Men. Hip-Hop. 'Candle In The Wind.'

The bump of hip-hop and thrash of grunge may dominate our sonic memory of the '90s, yet the hits that bookended the decade were soaked in smooth. In late January 1990, Michael Bolton's syrupy ballad "How Am I Supposed to Live Without You" became the decade's first new No. 1, and some 3,500 days later, Santana and Rob Thomas' "Smooth" began its surprising 12-week run at the top.

This was no anomaly. More than any previous decade, the '90s saw more No. 1 songs enjoy multiple-month runs, and the vast majority of them were croon-heavy ballads like All-4-One's "I Swear," Boyz II Men's "End of the Road" and Whitney Houston's "I Will Always Love You" (11, 13 and 14 weeks at No. 1, respectively). While the album charts heralded the rise of "alternative" through hip-hop's spreading popularity and rock's rediscovered grit, the singles chart walked a different beat. Among the No. 1s, there was no Nirvana, no Dr. Dre or Snoop Dogg, no Pearl Jam, no Wu-Tang Clan. There was, however, Mariah Carey. Lots and lots of Mariah Carey.

It's only fitting that the decade's undisputed hitmaker would also be the first legitimately new star of the '90s. Holdovers from the '80s dominated the first half of 1990: Paula Abdul, Taylor Dayne, Roxette. Then, in early August, Carey began a four-week run with "Vision of Love," the first of a record 14 No. 1s for the decade, including "One Sweet Day," her holiday season collaboration with Boyz II Men in 1995. "Day" spent 16 weeks at No. 1 and the two acts' dual success seemed apropos; during the '90s, nearly one of every six weeks saw either artist with the top single.

Their success, along with that of such artists as Janet Jackson, Toni Braxton, Monica and Brandy, was a stunning sign of how far R&B had come since the relative doldrums of the '80s. But that only tells part of the story, since R&B's dominance in the '90s was heavily influenced by the sound and swagger of its less-reputable kin, hip-hop.

Though rap album sales bum-rushed the pop charts, reluctance among top 40 radio programmers prevented rap singles from enjoying the same crossover success. The few exceptions in the early '90s were textbook one-hit wonders: Vanilla Ice's "Ice Ice Baby," Marky Mark's "Good Vibrations," P.M. Dawn's "Set Adrift on Memory Bliss." The first respected rap star to score a No. 1 was Sir Mix-a-Lot in the summer of 1992, with "Baby Got Back," but it would take another three years until another rapper returned to the top (Coolio with "Gangsta's Paradise").

MCs may have had it tough but hip-hop's production aesthetic enjoyed an easier time, especially as it all but took over uptempo R&B dance hits by 1995. Eighties rap icon Slick Rick played an indirect hand with that shift when Montell Jordan used the beat from the rapper's "Children's Story" for "This Is How We Do It" (seven weeks at No. 1) and then, mere weeks later, TLC's breakout hit "Creep" used samples from Rick's "Hey Young World."

It wasn't until 1996 that rap artists began to regularly occupy the No. 1 spot with any frequency, as Bone Thugs-N-Harmony and 2Pac began trading weeks with Braxton and Celine Dion. Even then, all of them had to fall back that summer as Los del Rio's "Macarena" swept in for 14 weeks to become the decade's biggest gimmick hit.

No less strange was how the specter of death hung over the No. 1s of 1997. Following the shooting death of rapper the Notorious B.I.G. in March, his "Hypnotize" single began a three-week run at No. 1 in May, only to be eclipsed by Sean "Puff Daddy" Combs and Faith Evans' B.I.G. tribute song, "I'll Be Missing You" (14 weeks). Then they were outdone by Elton John's rerecording of "Candle in the Wind" to honor the passing of Princess Diana in late August. John's original 1974 version wasn't released in the United States, but his 1997 remake reached No. 1 in October and didn't relinquish its hold until mid-January 1998.

By decade's end, some familiar faces still held on. There was Carey, of course, with Jay-Z riding shotgun on her late-1999 single "Heartbreaker," while TLC scored two No. 1s that year with "No Scrubs" and "Unpretty." But the upcoming class of the 2000s was also beginning to make its voice heard, quite literally in the case of Christina Aguilera and her piercing vocals on "Genie in a Bottle," a summertime No. 1 for five weeks. Earlier in 1999, fellow former Mouseketeer Britney Spears had already enjoyed two weeks at No. 1 with ". . . Baby One More Time." Meanwhile, as one-third of Destiny's Child, Beyoncé scored her first No. 1 when the group's "Bills, Bills, Bills" spent a week at No. 1 in July.

Santana's "Smooth" may have crushed all comers at the end of the decade but the changing sound of pop music, heard on Timbaland's slurpy, choppy beats for "Bills, Bills, Bills" and the unforeseen prescience of Cher's Auto-Tuned vocals on her 1999 single "Believe," hinted that as much as "smoothness" ruled the stoop in the '90s, sharp curves awaited ahead. Technology, within the studio but more important, throughout the music industry and larger society, was about to bring a new millennial groove crashing in on everyone.