It is possible to manage nodes that are remote from each other i.e. East coast - West coast, in a single grid.
You can create a grid with nodes that are remote from each other as long as you have a stable WAN network that is shared between the nodes in the grid.
The nodes do not need to be on the same subnet, just a stable WAN connection that can communicate with the grid master and the other nodes in the grid.
Note: WAN links can effect remote replication and tuning considerations may be needed, please review the link below for more details: