Mobility Historically, when life got too difficult in a given part of the country, us Americans were perfectly willing to pack our bags and move (to California, as it were). From a labor mobility perspective, this is brilliant - labor shortages in North Dakota are solved by surpluses in Nevada, Pennsylvania by Florida, etc. There is a bit of a downside to this - we need to be willing to tolerate massive de-population in some states (and, as it turns out, we are willing.). Admittedly, the housing crisis has put a bit of a dip in this mobility - people can't Just Move when they have an underwater mortgage to deal with - but lets ignore that for the nonce. Borders The thing is, in the end, us Americans tend to move around only within America . Its pretty difficult to go further East or West - not too much happening in the Caribbean, and Siberia sucks. North and South, well, Canada and Mexico. Seriously, its not that there is anything wrong with ei...