Two years ago, Billboard celebrated the 50th anniversary of the Billboard Hot 100 chart. As explained in a special feature at the time on billboard.com, "After nearly two decades of tracking songs distinctively by sales or plays (on jukeboxes and at radio), the Hot 100 was the first list to measure popularity by incorporating both radio play and sales."
The most venerable gauge of songs' national success launched with the Aug. 4, 1958, ranking, led by Ricky Nelson's "Poor Little Fool." When the chart reached the half-century mark, Katy Perry  reigned with the 961st title to top the tally, "I Kissed a Girl."
When Billboard highlighted the top accomplishments of the chart's first 50 years, Chubby Checker 's "The Twist," the only title to reach No. 1 in two chart runs, in 1960 and 1962, stood as the survey's all-time No. 1 title. Santana's 1999 smash "Smooth," featuring Rob Thomas, ranked second. Bobby Darin's 1959 No. 1 "Mack the Knife" placed third.
In just two years, however, music has continued to evolve. Just as the Hot 100 itself has segued over its 52 years from melding reported radio playlists and sales of 45s to its current formula measuring electronically monitored airplay and digital download and streaming data, according to Nielsen Music, a look back just 24 months reinforces that, in the music business, change may be the only constant.
Consider that, as of Aug. 4, 2008:
Randy Jackson, Paula Abdul and Simon Cowell had judged the then-most recent episode of "American Idol." "Glee" was nine months away from expanding Fox's Tuesday night - and, subsequently, Hot 100 - dominance.
Justin Bieber  was an unsigned 14-year-old building an audience virally on YouTube.
Lady Gaga  had yet to assemble her army of little monsters and appear on the Hot 100.
In honor of the chart's 52nd birthday today (Aug. 4), here is a look at notable records achieved in the two years since we feted the golden anniversary of Billboard's signature songs survey.
FOREVER 'YOURS': On the Hot 100 dated Aug. 29, 2009, Jason Mraz 's "I'm Yours" set the mark for most weeks logged on the list. That week, the song spent its 70th week on the chart, passing the previous record-holder, LeAnn Rimes ' "How Do I Live." Mraz's song wound up totaling 76 chart weeks.
Here is a recap of the titles to tally the longest chart lives in the Hot 100's history:
76 weeks, "I'm Yours," Jason Mraz, 2008-09
69 weeks, "How Do I Live," LeAnn Rimes, 1997-98
65 weeks, "You Were Meant for Me/Foolish Games," Jewel, 1996-98
64 weeks, "Before He Cheats," Carrie Underwood, 2006-07
62 weeks, "You and Me," Lifehouse, 2005-06
"I had little expectations about 'I'm Yours' on the radio, but I was wrong," Mraz told Billboard in August 2009. "People just kept getting on board.
"I'm still blown away, humbled by the success of my happy little hippie song."
SEEMINGLY 'E.N.D.'-LESS: The same week that Mraz achieved his milestone, the Black Eyed Peas  made Hot 100 history in the chart's coveted top spot.
On the Aug. 29, 2009, chart, the quartet spent an unprecedented 20th straight week at No. 1, as "I Gotta Feeling" inked an eighth week at the summit. "Boom Boom Pow," the first single from the album "The E.N.D.," had led for 12 weeks directly prior to the command of its follow-up. The group passed the 19 consecutive frames that Usher  spent at No. 1 with "Yeah!" and "Burn" in 2004.
"I Gotta Feeling" would go on to total 14 weeks atop the Hot 100, bringing the Black Eyed Peas' record streak to exactly six months - 26 weeks - in charge of the chart.NEW DIRECTIONS: Following the series premiere of "Glee,"  two songs by the show's cast debuted on the Hot 100 dated June 6, 2009, led by its highest-charting title to-date, its cover of Journey's "Don't Stop Believin' " at No. 4.
One year and three weeks later, the "Glee" cast had totaled 64 charted titles, the seventh-most appearances among all artists in the survey's archives and second among groups only to the Beatles' 71.
With the series' second season premiere set for Sept. 21 , the TV troupe could soon pass the Fab Four for most Hot 100 entries among groups all-time.
Here is a look at the acts with the most Hot 100 appearances to-date:
108, Elvis Presley 
91, James Brown
74, Ray Charles
73, Aretha Franklin
71, the Beatles
67, Elton John
64, "Glee" Cast
63, Stevie Wonder
59, Lil Wayne
DEFYING GRAVITY: One of the songs that the "Glee" cast has sent onto the Hot 100 is "My Life Would Suck Without You." The ensemble's version reached No. 51 in December 2009.
Earlier last year, on the Feb. 7 chart, Kelly Clarkson 's original recording of the song vaulted 97-1. The cut was the second song following the Hot 100's 50th anniversary to establish the mark for largest chart leap to No. 1, following Britney Spears ' "Womanizer," which bounded 96-1 in October 2008.
Here is a listing of the songs to make the biggest vaults in the Hot 100's history:
Positional Gain (Chart Move), Title, Artist, Year
96 (97-1), "My Life Would Suck Without You," Kelly Clarkson, 2009
95 (96-1), "Womanizer," Britney Spears, 2008
91 (94-3), "Beautiful Liar," Beyonce & Shakira, 2007
88 (95-7), "Smack That," Akon featuring Eminem, 2007
85 (96-11), "Cowboy Casanova," Carrie Underwood, 2009
85 (100-15), "Jai Ho! (You Are My Destiny)," A R Rahman & the Pussycat Dolls featuring Nicole Scherzinger, 2009
This March, Taio Cruz  rocketed 53-1 on the Hot 100 with his maiden chart entry, "Break Your Heart," featuring Ludacris. The song's coronation marked the biggest jump to No. 1 for an artist's first Hot 100 charted title, passing Clarkson's "A Moment Like This," which roared 52-1 in 2002.
THAT'S A RAP: On the Hot 100 dated May 22 this year, Eminem  bowed at No. 1 with "Not Afraid." While the song was the 16th to start at the apex, it became the first rap title to earn the honor.
Eminem has since returned to No. 1, holding sway the last two weeks with "Love the Way You Lie," featuring Rihanna . The song is the 988th Hot 100 No. 1, continuing the march toward an upcoming milestone, the as-yet-unknown 1,000th Hot 100 leader.
Will that landmark song be by an artist who's enjoyed a view from the top before, like Usher or Justin Timberlake ?
Or, will it be by a star artist who's yet to achieve the distinction of a Hot 100 No. 1, such as Taylor Swift  or Justin Bieber?
Or, by an act, like Lady Gaga just two years ago, that's yet to appear on the survey?
The fun will be in finding out, as it has been every week of the last 52 years in the pages, in paper and online, of Billboard.
- Chart Beat