To keep something or somethings in sounds like a viable reason though I would have left a few wizards maybe Unspeakabkes back to keep an eye on things.
Sill Harry hasn't felt any magic even in the US.
I'll assume that he'll find out the rest of the Wizarding world took a shot at colonizing their own planet which given their fear of normals I can see happening.
Still wished he wasn't alone but Kim seems like a good ACC.
dennisud
Author's response
Well, Harry has been able to use magic in the US in his attempt to keep up on what he knows and to try and attract wizards and witches attention. It's just that he hasn't been successful in making contact for a pretty good reason. This will be revealed in a few chapters.
I encourage you to keep reading and if a chapter seems like its boring or slow, that's mainly because that particular chapter is either a bridge to the rest of the story or a setup for an event that's going to happen later on.
Rob