Project ELF, the extremely low frequency radio system for sending an emergency war order message to submarines. Three new ELF antennae would be built in upper Michigan—one of them twenty-eight miles long, the others about fourteen miles long. Project ELF was a scaled-down version of SANGUINE, a plan that had been strongly backed by the Navy. It would have buried six thousand miles of antenna, four to six feet deep, across an area covering almost one third of the state of Wisconsin.
