By the spring of 2005, the music industry was ready to write off Mariah Carey. After a string of commercial setbacks in the early 2000s, critics and radio programmers openly wondered if the vocal powerhouse had run her course. Then came a simple, heartbeat-like drum machine kick, a few piano chords, and a lyric that would define the decade.

On this day in 2005, Mariah Carey’s “We Belong Together” cemented its place at No. 1 on the Billboard Hot 100. It was on its way to a historic 14-week reign at the top spot. It wasn’t just a hit record; it was the ultimate pop culture resurrection, later officially crowned by Billboard as the Song of the Decade.

Why the Song Was a Hit

Co-written and co-produced with longtime collaborator Jermaine Dupri, “We Belong Together” was actually the last song recorded for The Emancipation of Mimi album. Carey and Dupri captured lightning in a bottle by fusing two different worlds. They combined a classic, heart-wrenching R&B ballad with a sleek, contemporary hip-hop rhythm.

What made the track an instant classic was its brilliant musical nuances. Mariah traded her traditional soaring verses for a rapid-fire, conversational singing style that mirrored the hip-hop beats of the era. She also integrated clever nods to old-school soul, explicitly name-dropping classics by Bobby Womack and The Deele. Finally, she built tension until she shifted the entire song up a full octave for the final chorus, perfectly capturing the raw desperation of heartbreak.

Making Music History

When “We Belong Together” took off, it didn’t just climb the charts; it completely broke the tracking systems. It went on to spend 14 non-consecutive weeks at the top spot, which tied for the second-longest-running No. 1 in Hot 100 history at the time.

The song’s cultural saturation was unprecedented, as it became the first song in history to cross 200 million listeners on the radio in a single week. It also achieved unparalleled chart dominance, becoming the first song to simultaneously top eight separate Billboard charts, including Pop, R&B, and Rhythmic radio.

The track ultimately earned Mariah two Grammy Awards and propelled her album to massive multi-platinum status. Over two decades later, when those opening piano chords play, the collective nostalgia is a reminder of a summer when Mariah Carey had the entire world singing along in unison.