[rsj_hn]

You are right that "West of the Mississippi" is not the actual boundary, which is why I said "majority of the land". The actual boundary curves, being farther west in the Gulf and almost touching the Mississippi in the North, but "Western half of the US" is as good a description as any.

Point being, a lot of people who grow up in the Eastern Half of the US think the Western half has a similar climate, when it really doesn't. It really is an arid climate and the difference between East and West is rather stark.

Here you can take a look at a map of precipitation:

http://www-das.uwyo.edu/~geerts/cwx/notes/chap17/rain_usa.ht...