The IRS provides data regarding migration patterns in the U.S. at various levels including county-to-county and state-to-state. The MCDC has developed a pair of closely related irsmig profile web applications that faciliate accessing these data at the county and state levels.
The county level app can be accessed at http://mcdc2.missouri.edu/cgi-bin/broker?_PROGRAM=websas.irsmig_menu.sas&_SERVICE=appdev&st=29. It contains a link to the state level profiles at http://mcdc.missouri.edu/websas/irsmigpros/US%20State-to-State.html.
The data for these applications goes back to 1999-2000 for the county level data and to 2004-2005 for the state level. We appeared to be in a regular pattern where the IRS would release a new year of data in the fall of each year. We expected to be able to get data for 2008-2009 in September of 2010, but it never arrived. The IRS has told us that they are not sure if they are going to be able to provide these data sets any more. However, they have provided data to the Census Bureau for the FSCPE population estimates program. Through Matt Hesser, the Mo state demographer and FSCPE participant, we have been able to secure migration data at the state level for the US and at the county level for Missouri. We have added the state level data for the new year to our state-to-state profiles. We hope to add the new county level data for Missouri only within the next few weeks. We have no idea if or when the folks at the IRS will provide us with a national county-to-county level set of data for 0809 and beyond.