Justice League Of America #78 (February 1970) [National Periodical Publications]
On the Newsstands today in 1969 was this issue of the JLA. According to Mike's Amazing World of Comics (www.dcindexes.com), this issue shipped on Dec. 11, 1969.
So, what's interesting about this issue? It actually is a great issue showcasing superhero comics and comic book fandom of the time.
First, the JLA story begins with the river running near Star City accidentally catching fire because of its polluted state and the superheroes needing to put it out. The whole story by Denny O'Neil is one of the many of "relevant" comics that were the vogue at this time.