"Richard Harrison" wrote (clip):
I am looking at a broadcast allocation book prepared
by Cleveland Institute of Radio Electronics in 1959.
Many changes in stations and coverage since then,
but the book contains an estimated ground conductivity
map for the U.S.A. which probably has changed very little
since then.
________________

The FCC's version of the US ground conductivity map is available on line at
http://www.fcc.gov/mb/audio/m3/

RF