What is the border of Elsewhere and the community called in The Giver?

The boundary itself does not have a name. Even the world beyond does not have a name - it is simply "Elsewhere."  Although "Elsewhere" is referred to multiple times in the book, the boundaries or borders of the actual community and "Elsewhere" are not discussed.

As Jonas and the Giver plan Jonas's escape, we begin to learn a bit more about their world, but not much. We know that the Giver periodically travels to nearby...

The boundary itself does not have a name. Even the world beyond does not have a name - it is simply "Elsewhere."  Although "Elsewhere" is referred to multiple times in the book, the boundaries or borders of the actual community and "Elsewhere" are not discussed.

As Jonas and the Giver plan Jonas's escape, we begin to learn a bit more about their world, but not much. We know that the Giver periodically travels to nearby communities, so we know there are other communities like Jonas's, but we do not know how many there are or how much area they cover.

Once Jonas begins his "journey to Elsewhere" as he calls it, he has to travel really far. He bikes for days before finally saying in Ch. 23, "Yet he felt it; felt that Elsewhere was not far away." By this time, however, he has already been experiencing weather and landscapes—things which he had not experienced in his community. So, this blurs the line a bit for readers, who have to then wonder where his community's control ends and where "Elsewhere" begins. Is "Elsewhere" only where other people are outside of the community? Or just anywhere outside of the strict control of Jonas's community? That is never made clear.