Which Northern American Country is narrow enough to be considered an isthmus?

Question

Which Northern American Country is narrow enough to be considered an isthmus?

Answer 1

there is no northern American country is called an Isthmus. I think the answer is panama. But then Panama is in the central America.

Answer 2

The only isthmus in the American hemisphere is Panama.  There is no country in North America which could be considered an isthmus.  Panama is technically in Central America.

Answer 3

Panama