So, Robb and I are driving across this gigantic country, and have
tried to include letterboxing in our activities.

I wanted to share an image from the "Corny Letterbox" site. The sign
is actually one of the clues...

Follow this link, and click away:
http://photos.groups.yahoo.com/group/LbNCA/lst

Cheers!
Lisascenic and Robb