Summerland used to be a horse ranch until Oliver Bird inherited it in the 40's. With Cary Loudermilk's help, Oliver converted it into a facility to shelter mutants. Upon Summerland's completion, Oliver and Cary began their pursuit for more mutants like themselves to fill the facility. Unfortunately, it was during this time that they encountered a mutant named Walter, who sought only to destroy everything they built and stood for.  Walter then joined a Division 3, a government organization and nemesis of Summerland.
Since then, Summerland has fallen under the leadership of Oliver's wife, Melanie Bird. Although, Oliver had been trapped in the Astral Plane for twenty years, his presence within the community never ceased to be felt as his voice could be heard on the espresso machine and in the elevator. Under Melanie's leadership, Summerland has rescued numerous mutants from Division 3 and trained them to control their abilities.
After the Shadow King escaped in Oliver's body, Summerland merged with Division 3 in a truce to find and stop dangerous mutants. The Summerland mutants were also able to convince Division 3 that most mutants are harmless and only wish to live their lives in peace. 
† denotes deceased:
- While Summerland does not appear in any of the Marvel Comics, it identically serves the same purpose of Xavier's School for Gifted Youngsters.