... boy- the US Navy sure was happy to get into the nuclear game with their fleet of atomic powered ballistic missile submarines! The last word in Mutually Assured Destruction these big 'boomers' could hide unseen and invulnerable for months beneath the salty brine of the world's oceans. Only one problem- how to send a radio signal to the submarines to launch their missiles and obliterate the enemies cities? Normal radio waves do not penetrate very far into water.
The obvious answer was to build the world's biggest and most powerful radio antenna! Then use Extremely-Long-Frequency radio waves to zong out simple messages to the fleet anywhere in the world! Messages like "hi, we're fine" or "holy shit- Launch!" In fact it was such a great idea that they built several such stations like these seen here in the State of Maine and the Western tip of Australia.
note: much hoop-la has been made of the Soviet 'dead-hand' doomsday system; well, one would assume that if the US 'boomers' could not receive any sort of signal from home than a similar launch protocol would be initiated.
here are the map coordinates for Cutler Station, Maine- so you can see it on Google Earth:
44°38'54.70" N 67°16'26.08" W