>>81254671Fawcett's characters wouldn't get revived till the early 1970's. And there they just placed Captain Marvel and the rest on another Earth called Earth-S.
In the early 1980's Roy Thomas went all out with Earth-2 stuff for All-Star Squadron and revealed that Earth-2 was where all the Quality Comics characters came from, and had their own Plastic Man and Blackhawk. I think pretty much every Golden Age character DC had was now on Earth-2 except for the Fawcett ones. And then Roy Thomas decided to send off the Quality Comics heroes to Earth-X, where it's pretty much implied everyone of them except for the Freedom Fighters (Uncle Sam, Phantom Lady, etc) died in battle against the Nazis.
By the time Crisis on Infinite Earths was going to happen, DC somehow got ahold of the Charlton characters. Since COIE was under way, they briefly show the Charlton Earth (Earth-4) in the miniseries, and then eventually merged the Earths of Charlton, Fawcett, Quality, Golden Age DC, and Silver/Bronze Age DC into one.
And that's when it was all on one Earth.
After that, Milestone and WIldstorm and Impact (90's versions of the Archie superheroes) were separate Earths from the DC Earth, but then Milestone got folded into the same Earth during Infinite Crisis, I guess. There was also briefly Red Circle comics which was also another attempt at Archie superheroes, but this time existing in the DCU. And then Wildstorm got folded in during Flashpoint/New 52.
