I don't normally post pictures this big but this one needs it.  It's pretty clear where the red zones are here:  CA, NV, AZ and FL.  This is the 2007 foreclosure rate map for the entire United Stated (by county I believe).  All of OH, half of MI and most of TN and CO are also pretty hard hit.

I'm not sure the cause and effect on CO and TN, but the OH and MI problems seems to stick out here as the steel belt, er, rust belt.  In the commercial world I have not looked at Michigan in a long time because long before the subprime crisis it had alreayd been blacklisted by most lenders for commercial properties.  Other than that, it seems that it is clear that there is a notable concentration in urban areas compared to rural counties (there is next to nothing of note in the strip that runs from ND south all the way through TX to Mexico).  I guess farmers didn't get so caught up in this subprime mortgage craze...

The map is courtesy of Torto Weaton, the research arm of CBRE, though they aren't the original source, they just added to it.  Their addition to this map that is not residential related is those 12 black down arrows.  They are the only industrial real estate markets in the country that are down from 2006 in Torto Wheaton's rent index.  That's a big difference from the residential market, whre there is a lot more red on this than those black arrows.  The commercial market continues to hold up reasonably well, especially for rental rates, even despite a liquidity crunch in the lending markets.