Mike, Lonna Atkeson, and I are writing a book and as part of the research for it I looked at data on residential mobility from the Census. The data are pretty amazing and potentially have very important implications for voter registration and election administration.  Here are the key points:

1. The number of people moving between states has declined dramatically over the past decade, from roughly 7.5 million per year from 1998 to 2005 to 4.8 million per year in 2007 – 2009.
2. Same county moves slowly increased over the 2000s, from 21 million in 2000 to almost 25 million in 2009.
3. Intrastate moves to a different county have also plummeted, from between 7.4 and 8 million moves in 2000-2007 to 6.3 million in 2008-2009.

For election administrators, this means that keeping election rolls clean within a county are likely to be more difficult, as people move about the county and that rules regarding registration portability within a county are critical.  Rules for provisional voting, for instance, are likely to be more important, as are efforts to update registrations through the change of address process.

The question of how provisional voting changed between 2006 and 2010 is one that should be studied after the 2010 election data are all in.  In addition, these changes in mobility suggest that thinking about voter registration modernization means thinking about how to best keep everyone accurately registered — short moves and large — and that modernization is even more important than ever.  Finally, it will be interesting how mobility changes or doesn’t change between 2010 and the 2012 elections.