Atlas - Red Line
Since the Red Line is a continent it is very likely that there's lots of places where people live. However not a single one of such places has been shown nor was anything about such places mentioned so far. So there's also the possibility that the entire Red Line is unpopulated. Hopefully something more will be explained about it at some point.
Places already visited by a Straw Hat Pirate:
Places not yet visited by a Straw Hat Pirate:
None been mentioned so far. It that should change at some point, it'll be mentioned here.