bobmark - 4:03 pm on Mar 3, 2003 (gmt 0)
I'm glad to hear that I'm not the only one.
I had thought of political events as an obvious explanation, OntheEdge - as 70% of the Canadian population lives within 100 miles of the Canada/U.S. border, we do tend to notice American political concerns - but if that's the explanation, the concerns of the U.S. population apparently only affect their surfing on certain days of the week.
john5, I too tend to try and interpret traffic patterns but, like you, am frequently stumped. One thing I have noticed is that geography seems to have become more important as my U.S. sales - as opposed to traffic - has become very much East Coast/West Coast with little coming from the centre of the country (yes, I know that the East and West Coast populations are very dense relative to the centre, but still the pattern seems to exceed mere population distribution).