Denying someone visitors would be cruel and unusual punishment. Making visitors drive for two days (or fly for two hours) in order to visit, though, isn't.
Think about it this way: in the days before motorised transport, were prisoners always kept within easy travelling distance of their relatives? I think not, and it wasn't cruel-and-unusual then.
For practical purposes, though, Montana to California is a bit too far. But Nevada spends only $20K, and there's not much of Calfornia which isn't within a reasonable daytrip of somewhere in Nevada.
Mexico probably spends even less, though contracting prisons out to Mexico might cause genuine constitutional issues...
Think about it this way: in the days before motorised transport, were prisoners always kept within easy travelling distance of their relatives? I think not, and it wasn't cruel-and-unusual then.
For practical purposes, though, Montana to California is a bit too far. But Nevada spends only $20K, and there's not much of Calfornia which isn't within a reasonable daytrip of somewhere in Nevada.
Mexico probably spends even less, though contracting prisons out to Mexico might cause genuine constitutional issues...