MI is the worst for rust as far as I have been able to tell. The Northeastern cars rust from the bottom up. Florida cars rust from the top down and inside out due to the salt air & condensation.
BTW - I am loving the cars I have found in North Texas thus far - rust is a foreign object around here
I am on my 3rd resurrection on N. TX cars and the combined rust on all three would not even fill up a 5 gallon bucket