[CQ-Contest] Boundaries Between ITU Zones 6/7/8

[Nat Heatwole]

For the first time in years, I will be doing a full effort in this
weekend's coming IARU contest and for the first time ever, I will be
doing it from a simi-competative station. One thing that I've always
wondered about IARU is how one is to tell whether a U.S. station is in
ITU zone 6, 7, or 8. Sure, W6 is clearly zone 6 and Florida is clearly
zone 8, but where exactly are the boundaries between the zones? From the
map that I have, the boundaries are for the most part vertical. In that
case, are they scaled to the Maidenhand grid squares? And if so, which
grids are in each zone?

This may seem a moot point, with U.S. to U.S. QSOs worth less than
inter-continental QSOs, but if the bands are trash, that might be all I
can muster, and it would really suck loosing multiple QSOs for something
simple like logging a station as zone 7 when they are actually zone 8
(even if they sent me the incorrect zone). Any ideas?

73!
Nat - WZ3AR