Harmonics and the North American Locations

[Chris Kuykendall]

A question for the 88th anniversary of the disappearance:

Is there anything technical about harmonics transmission that accounts for three of the credible North American radio recipients being located near major bodies of water...

(1) St. Petersburg, Florida, on the Gulf of Mexico;
(2) Toronto, Ontario, on Lake Ontario;
(3) St. Stephen, New Brunswich, not many miles upriver from the Atlantic;

...and two others being located in comparatively high-elevation plateau areas:

(4) Amarillo, Texas, about 3,600 feet altitude, no mountains nearby;
(5) Rock Springs, Wyoming, about 6,400 feet altitude nestled near the mountains?