Per U.S. Census ACS Estimates
These charts were created using the Census Flows Mapper
here in an attempt to identify those U.S. counties with the highest number of residents migrating to and from selected Bay Area counties. As can be seen, counties often have large two-way exchanges of residents with another county.
People migrate to and from the Bay Area from all over the country and the world, and this analysis does not reflect that. The analysis was done in good faith, but may contain errors and is subject to revision. All numbers derive from 2012-2016 ACS estimates and should be considered approximate with fairly large margins of error.