2 ms·The Chicago - Great Lakes connection is man made, so doesn't count per the methodology of the OP.by bryanlarsen 2y agoThe Chicago - Great Lakes connection is man made, so doesn't count per the methodology of the OP.Nevermark 2y agoSo North and South America are not the North and South Panama Canal Islands. Got it!Kon-Peki 2y agoThe permanently navigable connection is man made. It was seasonally connected (and navigable by canoe), requiring a very short portage the rest of the year.