http://en.wikipedia.org/wiki/Down_East
Claims that it is because sailing from Boston to Maine, one traveled down wind.
I had read (and accepted) that it was because older navigational charts were oriented with west up (as opposed to north). Wikipedia offers some more plausible possibilities here.
http://en.wikipedia.org/wiki/Cape_Cod#.22Upper.22_and_.22Lower.22
Thanks.
Steven Wright says “Maine is nice but it”s also the setting for most of Stephen King’s novels.”