Been thinking about Monster Squad (1987) lately ('tis the season), and it struck me that this movie assumes that the kids would have been familiar with black-and-white Unviersal Monster movies from the 1930s-1940s. How likely is that? Where and how would they have seen these monster movies?
They'd be slightly obscure, but not impossibly so.
The Universal Monsters series technically continued until 1956 with the third Creature from the Black Lagoon feature (The Creature Walks Among Us); in 1957, Screen Gems packaged 52 of the movies from the series for television as Shock! or Shock Theater. This was followed by Son of Shock in 1958. (Note: not every movie was Universal, but they generally dominated the selections.)
This extended the newly burgeoning "horror host" late night show (Vampira had already been on, from '54 to '55), with different hosts for different markets, and were generally strong successes. An example reported in 1957:
In New York, a special Trendex made on October 3 and 4 showed that WABC-TV, previously an also-ran in the late-night film showings, built itself a new audience. On opening night, with "Dracula", the outlet drew a 8.8 rating and a 41.7 per cent share, representing a 450 percent hike in the station's rating and a share jump of 338 per cent over those in the time period the previous month.
The Universal Monsters in particular held strong TV popularity all the way through the 1960s before petering a bit after, although Mel Brooks's Young Frankenstein parody movie came out in 1974, and there were numerous toy sets, like the Official World Famous Super Monsters made by AHI in 1973 (with official licensing from Universal) or the (unlicensed) Mad Monsters line from Mego, or the Remco figures from 1979.
While TV showings continued in the 1980s, there was a gap in enthusiasm until 1991 when Universal Home Video brought out The Classic Collection on VHS tape. So, yes, Monster Squad (1987) was not timed well in terms of hoping a younger audience would know the movies well, but this was perhaps reflected in the sales numbers (domestic earnings of $3,769,990 on a estimated budget of $12,000,000) and the movie only became successful later as a cult classic.
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Brunas, J., Weaver, T. (2011). Universal Horrors: The Studio’s Classic Films, 1931–1946, 2d Ed.. United States: McFarland, Incorporated, Publishers.
Neibaur, J. L. (2017). The Monster Movies of Universal Studios. United Kingdom: Rowman & Littlefield Publishers.