Originally Posted by
televisor
There are approximately 200 countries in the world. Subtract a handful, and most are still eligible for automatic validation.
And the Visa is not in effect valid. It is only valid during the dates printed on the Visa. Your US admission status might still be valid, but the Visa is NOT valid.
And you have similar situation if your studies or training program are extended: your Visa might be expired, but you can still travel to Canada/Mexico without having to return home and obtaining a new Visa to cover the remainder of your visit.
Most may, but a lot may not. And that goes beyond for just those from blacklisted countries. But you're welcome to open another thread on that to try to get that discussion going during these interesting times.