>Does the US have no absolutely mechanism at all for restricting travel if there is an emergency? What would they do if there was an invasion or a pandemic wher

>Does the US have no absolutely mechanism at all for restricting travel if there is an emergency? What would they do if there was an invasion or a pandemic where there was a much higher proportion of people dying? I'm not a lawyer, but I really don't think it does. As mentioned in a sibling comment, flights might be grounded, but that doesn't stop you from getting in your car and driving. Freedom of movement is enshrined both in the constitution and in the culture to a very high degree.