(Edited below, because it turns out I am not very good at this.)
A reader writes: “Listening to these AT40s from late ’74 leads me to wonder whether you’ve ever done a blog piece on the weirdness of the fourth-quarter #1 plunges that year.”
Not until today, no.
In days of yore, the methodology used to compile the singles charts was not nearly so precise as it is now. It’s arguable that the song designated #1 in many weeks of the 1970s was no more or less popular than several other songs at the top of the charts at the same time. But Billboard had to choose one, and so it did.
In 1974 and 1975, 35 different records reached #1 in each year. Out of the 70 chart-toppers, only 23 lasted longer than one week at the top. (The longest run was four weeks, by the Captain and Tennille’s “Love Will Keep Us Together.”) Between January and April 1975, an 11-week stretch, there were 11 different #1 singles on the Hot 100. In such a volatile time, scoring a #1 hit was great for bragging rights (and it’s what history remembers), but it didn’t necessarily mean you were the indisputable ruler of all the land.
There’s another kind of chart volatility involving moves within the chart. Today, records zoom up, drop off, and move around in patterns that look erratic to old-time chart geeks. Back in the day, most records followed a familiar curve—a couple of big leaps while below the Top 40, and once in, a steady climb a few places at a time, sometimes with a big leap or two in mid-chart. A period at the peak was followed by a falling-out period usually far shorter than the climb. Although middle-of-the-chart records could plunge dramatically, more often than not, the first week of falling at the very top of the chart meant a very small drop. When a record fell from #1, it would often remain in the top 5.
But not always. In the fall of 1974,
six seven records took uncharacteristically large dives from the #1 spot.
—For the week of September 28, “Can’t Get Enough of Your Love Babe” by Barry White fell from #1 to #12.
—For the week of October 5, Andy Kim’s “Rock Me Gently” did the same thing.
—On October 26, “Nothing From Nothing” by Billy Preston fell from #1 to #15, which I neglected to mention when this was originally posted. Our friend Steve Orchard caught the omission, and I’m grateful, albeit rather embarrassed.
—On November 2, “Then Came You” by Dionne Warwick and the Spinners, which had taken a then-record 14 weeks to reach #1, plunged all the way to #15.
—The next week, November 9, “You Haven’t Done Nothin'” by Stevie Wonder fell from #1 to #12.
—The week after that, the same thing happened to Bachman-Turner Overdrive’s “You Ain’t Seen Nothing Yet.”
—Two weeks later, on November 23, John Lennon’s “Whatever Gets You Through the Night” did the same damn thing yet again: from #1 to #12, the fifth #1-to-#12 drop in nine weeks.
After that, things calmed down. The next couple of dethroned #1 songs fell to #2, and then we’re into 1975. A number of songs fell from #1 to #6 or #8 during that January-to-April stretch we mentioned above but nothing so spectacular as the October/November plunges.
(Related, and at about the same time: Wikipedia says “Junior’s Farm” by Wings had one of the all-time biggest falls out of the Hot 100, but it deserves an asterisk. Yes, the song was at #17 on January 25, 1975, and gone the next week. However, its B-side, “Sally G,” had been added to its chart listing in December, after “Junior’s Farm” had been on the chart for a couple of months. And on February 1, 1975, “Sally G” was listed as a new entry, all by itself, at #66, although it kept the same catalog number, so “Junior’s Farm” was still on the other side. That means “Junior’s Farm” actually fell from #17 to #66, which is a big plunge out of the Top 40, but not especially crazy within the scope of the Hot 100.)
What’s the reason for this brief period of volatility? Beats the hell out of me. If I were Nate Silver, I’d do a mathematical analysis and see what kind of patterns I could find in all the chart data. But I am only a dumb-ass disc jockey who got a D in algebra, so “I dunno” is the best I can do. Guesses from the readership are welcome.