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"migration patterns by state or by county for the entire United States and are available for inflows—the number of new residents who moved to a county or state and where they migrated from, and outflows—the number of residents leaving a county or state and where they went"
"a web mapping application intended to provide users with a simple interface to view, save and print county-to-county migration flows maps of the United States. The data are from the 2006-2010 American Community Survey."