> NZ is about the same size and population as Oregon, so a single state could choose to do it, if they were willing to face up to the implications of the choice

> NZ is about the same size and population as Oregon, so a single state could choose to do it, if they were willing to face up to the implications of the choice. In the US, some of the relevant choices have to be made at the Federal level. For example, Oregon does not have authority to close state borders to travellers from other states or countries.