The US Census Bureau has released county to county migration for the 2005-2009 period. The data shows how people are moving around the US between counties. I was rather surprised to find out that only a bit over 1/3 of people who moved went to a whole new county. I would have guessed more than that. Maricopa County Arizona seems to have a lot of action going on. The received people from nearly 1,000 different counties around the US, but they also sent people to over 1,100 counties around the US. The realtors there must get a LOT of traffic. If you’d like to see the migration patterns for any particular county or even any particular state, you can download the excel spreadsheets yourself from this site.