If there’s one thing we know about the Golden Age, it’s that publishers chased trends even more than they do now. Superman spawned more superheroes. Batman bred an endless string of idle playboys with secret identities, not to mention masked vigilantes with a boy sidekick. When Archie became a hit, everyone tried a knockoff. Everyone had a red, white and blue-clad patriotic hero, most companies had a crime-fighting bowman.
So how come it didn’t happen with the superhero teams?
The Justice Society of America debuted in 1940 and lasted until 1951, a very respectable run. The only super-teams that followed were DC’s own Seven Soldiers of Victory (fourteen issues) and Timely’s half-hearted All-Winners Squad, which got two post-war issues of All-Winners before that book became a teen comic. 
It’s not like other companies didn’t have plenty of superheroes they could have combined, and it’s not as if they didn’t crossover. The original Human Torch fought Namor; Quality’s Spider Widow and Phantom Lady locked horns over their mutual interest in fellow superhero Raven. Fawcett Comics had the Marvel Family (I don’t think of them as a “team” any more than I do Batman and Robin) and several crossovers between characters, but no JSA equivalent.
It seems such a logical option, it’s puzzling why nobody took it.
The Silver Age was a lot less inhibited. Aside from DC’s adventure teams (Challs, Sea Devils, Rip Hunter’s crew) we got the 
Legion of Super-Heroes in 1958, followed by the JLA in 1960. Then came the Fantastic Four, the X-Men, the Avengers, the Doom Patrol, the Teen Titans and the reactivated Justice Society. It would only grow from then on, especially when the Big Two started adding multiple Leagues, mutant teams, etc. down the road.
I’m just surprised it didn’t happen sooner.
#SFWApro. Cover top to bottom by Everett E. Hibbard, Al Avison, CC Beck and Curt Swan.
I’ve often wondered about this, too. There was, of course, the one-shot (and unnamed) group of assembled heroes who appeared in that one story in the Prize Comics Frankenstein feature, which at least shows that people were thinking about this sort of thing a little. The fact is, crossovers of any sort between different series (other than closely linked series, like the different Marvel Family characters) were extremely rare- varying from nonexistent to occasional, depending on the company. My theory is that during that time the different features were too closely associated with their different creative teams to allow others to use the characters too often.
I’d never realised that. I mostly go for team books, so I probably would’ve been starving in the Golden Age.
Correct me if I’m wrong, but I was under the impression that many of the early superhero teams rarely functioned as teams as such. The whole team thing was just for a prologue and epilogue while each team member had solo adventures (or duo if one had a sidekick or similar e.g. Star Spangled Kid and Stripesy)
So there were few examples of a team acting together as a team until the Silver Age
Technically true. Even so, everyone getting together and working on the same overall mission is a marked difference from just having them all deal with solo features. For example in Leading Comics 5 the Seven Soldiers all get together to talk about the threat, divide up the various parts and go off together. So there’s a unity of action even if they get individual gigs.
I think the phrase “many of the early superhero teams” greatly overestimates how many early superhero teams there were.
Much to my surprise, Leading Comics 6 does in fact have the Seven Soldiers team-up hunting “The Treasure That Time Forgot.” Vigilante and Shining Knight follow one clue, GA, Star-Spangled Kid and their partners follow another. It then turns surprisingly into an early Hero vs. Hero slugfest.
Fawcett did have one appearance of the Crime Crusaders Club, with Captain Marvel Jr, Minute Man, Bulletman and Bulletgirl, in Master Comics #41.
If you want groups, probably the biggest of the 1940s are the Blackhawks. They were massive sellers, back then. Not superheroes; but, they paved the way for a lot of team dynamics in superhero comics. You also had Death Patrol, another aviation feature, at Quality Comics, with the first three stories by Jack Cole. Hillman’s Airfighters crossed around a little, though mostly hade separate adventures. Eclipse later made them a more unified group.
The real groups of the 40s were the kid adventure groups: The Newsboy Legion, The Boy Commandos, Daredevil’s Little Wise Guys, the Young Allies, Little Boy Blue and the Blueboys, Our Gang, Reg’lar Fellas….that’s where you found more of the group dynamic and some of those features outsold the superheroes. The Little Wise Guys ended up reducing their hero into a supporting character for their adventures (same with the Newsboy Legion and The Guardian).