The appearance of this ad for Bobby (Boris) Pickett's "Monster Mash" in a May 1973 Billboard indicates two things: that the 1962 single was exploding on the radio somewhere unexpected or that London Records was engaging in a very careful strategy to return the oldie to late October radio glory.
I'm going with both. The "Top Single Picks" column in the same May 12 issue reports "Monster Mash" as having caught fire in Milwaukee at WOKY-AM and WZUU-AM in early '73. This surely prompted London to start making noise about it only to get premature payoff when the song peaked (very respectably) at #10 in ... August. No, not October. Weird.
As for reasons why "Monster Mash" found new life in the early '70s, I'll stick with my notion of it being a desperately nostalgic time. Here's what Billboard says: "...maybe with Watergate and other scandals in the headlines, today's impressionable young music listeners find humor in the music. What else do they have to laugh about?" In the words of Pickett himself, who was rescued from the ski resort folkie circuit by the single's revival, its new success had to do with a country "crying out for laughter."
What I'd really like to know more about, though, is the nostalgic mentality of Milwaukee, which happens to be the fictional home of Happy Days, Laverne and Shirley, and That '70s Show. Is there anything to this or is it all just coincidence?