When you use the word "close" it means you shut down the boarders on all sides by land/air/sea and we become and isolated country
People have to go through customs and be checked out. They may have to have a passport and visa. Maritime vessels get checked by the Coastguard or Navy. Oh the inconvenience. You went from not possible to inconvenient. I am okay with inconvenient.
When you start trying to make any sense .. get back to me
Oh and not very good on the baiting