Nationally, yes it's "advised" because the Federal government can't demand it short of martial law or similar. That said, most States have required lockdowns o

Nationally, yes it's "advised" because the Federal government can't demand it short of martial law or similar. That said, most States have required lockdowns or shelter in place. In the US system of federalism, the state governors+legislators have much more control over what happens in their state than the President+Congress.