Here's a look back at a few issues of DC Comics' oldest super-hero groups....and a few times where they had "final endings"!
The Mystery Of The Vanishing Detectives
The JSA gather four famous detectives in Civic City to help them solve a case to find out who is the mysterious Key....and they did, but they had no idea that the JSA would be the vanishing detectives, as Flash, Green Lantern, Hawkman, Atom, Dr. Mid-Nite, Wonder Woman and Black Canary had this as their last published adventure of the team (with the next issue of the series changed to All-Star Western....and only Wonder Woman continued on in her own title, as well in Sensation Comics, with no explanation as to where the team was or what had happened to them).
The Defeat Of The Justice Society
This issue was a double ending, as new member (and Batman's daughter) the Huntress, explained what happened to the original team in the 1950s to Power Girl. How they were approached by a man claiming to represent the U.S. government, and showed them a satellite they could use as their headquarters, but attacked the team instead. The JSA found they were not really working with the U.S.A., but, in attempting to explain that, were forced out of functioning as the government wanted them to reveal their secret identities (which they were loathe to do). This issue also marked the last solo JSA story of the 1970s (though the team would still make the annual Crisis with their Earth-1 friends, the Justice League of America).
Last Days Of The Justice Society
The team gathered to deal with their losses after the Crisis On Infinite Earths....and found that they also lost soon after World War II?
How could that be possible?
Some leftover energy from Adolf Hitler, powering the Spear of Destiny was doing to doom the newly formed DC Universe....if the remaining members of the JSA didn't band together to fight to stop the end of the universe...or, Ragnarok as it had been called in the days of the Asgardians (which is what Hitler had summoned up in the 1940s as World War II drew to a close).
Spectre, Dr. Fate, Power Girl and the Star-Spangled Kid. While the Kid kept up with Infinity, Inc. (as Skyman), Dr. Fate, then Power Girl, joined the Justice League...
...there was no JSA for a time