The distances are measured. Each is the shortest great-circle distance from a real settlement to the exact curve of the line, computed against a committed public-domain gazetteer by the same engine that measures a paying customer's own.
The interpretation is a different kind of thing and we would rather say so than blur it. It is craft, written by hand in the tradition locational astrologers have refined since the nineteen seventies, and it describes what a place tends to support and to demand. It is not a prediction, and no line on any map decides what happens to a person.