NEW YORK • The longest-running No. 1 single in the 61-year history of Billboard's Hot 100 chart is not by Elvis Presley, The Beatles, Michael Jackson or Madonna.
And no longer is that record held by One Sweet Day by Mariah Carey and Boyz II Men, from 1995, or Despacito, a 2017 Latin smash by Luis Fonsi, with Daddy Yankee and Justin Bieber - both of which held the top spot for 16 weeks.
The new champion is as much a novelty song as it is a meme and a lesson in the state of music marketing: Lil Nas X's Old Town Road.
After its latest blast of remixes and videos, it notched its 17th week on Monday atop Billboard's flagship singles chart.
Although the song's lead has been slipping in recent weeks - Billie Eilish's bad guy had twice as many radio plays as Old Town Road - it was enough to lead Lil Nas X, 20, to a historic run.
Since it first topped the chart in April, the song consistently had huge numbers. It has blocked new songs by giants like Taylor Swift, Ed Sheeran and Shawn Mendes from reaching No. 1.
And the song has been a pervasive cultural phenomenon for much of the year, with an endless series of online memes - many generated by Lil Nas X.
The rise of Old Town Road - and the week-by-week maintenance of its chart position - is in some ways a story of an old-fashioned one-hit wonder, and in some ways a primer on the latest and most effective ways that music is promoted.
Almost from the moment that he rolled out the song late last year, as an independent act, it was an experiment in genre and viral marketing.
Using a backing track he bought online for US$30 (S$41), Lil Nas X - a college dropout from Atlanta whose real name is Montero Hill - created a "country-trap" hybrid, with a boomy bass, plucked strings and cowboyish lyrics about "horses in the back".
He began generating social media memes for the song, and it first became a hit on video-sharing app TikTok.
Thousands of young people made short clips mugging in cowboy hats and boots with his song playing in the background, tagging their clips #yeehaw.
"I promoted the song as a meme for months until it caught on to TikTok and it became way bigger," Lil Nas X told Time magazine.
By mid-March, he had signed to Columbia Records and first hit the mainstream news radar after Billboard removed the song from its Hot Country Songs chart, drawing criticism about the conservatism of country radio and accusations of racism.
But what made Old Town Road a lasting hit was its steady and strategic drip of remixes.
The first, with Billy Ray Cyrus, sent the song to No. 1 in April.
Then came Diplo's electronic version; another with rapper Young Thug and Mason Ramsey, the 12-year-old "Walmart yodelling kid", who was summoned awake one night to record his verse; and yet another featuring RM of K-pop group BTS.
Along the way were music videos, live appearances at Stagecoach Festival and on TV award shows, and Lil Nas X's constant feeding of the phenomenon with tongue-in-cheek tweets that rallied the audience to his side.
"Everybody stream all 79 versions of Old Town Road," he tweeted two weeks ago. "Let's break the record."
Mr Matty Karas, curator of MusicRedef, an online news aggregator, said: "This is a kid who understands how the Web works, how culture moves in 2019.
"He understands the magic of how to make something go viral."