I am working on a project about internal migration in the U.S. using the American Community Survey. As I browsed the data, I found the countyfip and migcounty1 variables, which seem to be very useful for generating county-level migration flows. However, it seems that many of the counties in the variables are not identifiable—those are coded as zeros along with N/A cases—for confidentiality reasons and/or technical reasons.
However, I also see that there is a MIGPUMA1 variable without a problem with the unidentifiable cases, but there are many cases where multiple counties consist of a PUMA.
Browsing and Googling, I found this [posting] about a crosswalk from County to PWPUMA and saw that Jonathan Schroeder, thanks to him, uploaded a crosswalk from county to MIGPWPUMA for 2010 (for 2012-onward IPUMS data) definition; the filename is “ipums_migpwpuma10_county_crosswalk.csv”.
I was wondering if I could also get the crosswalk from county to MIGPWPUMA for 2000 definition for 2005-2011 IPUMS data.