The American Community Survey (ACS) and the Puerto Rico Community Survey (PRCS) ask respondents age 1 year and over whether they lived in the same residence 1 year ago. For people who lived in a different residence, the location of their previous residence is collected. The metro-to-metro migration flows were created from tabulations of the current metropolitan statistical area of residence crossed by metropolitan statistical area of residence 1 year ago.
Metro-to-metro migration flows are available up to and including the release of the ACS 5-year 2016-2020 dataset. For more information, please see the ACS 5-year Migration Flows Break in Series notice.
Both current residence and residence 1 year ago are coded to the most current metropolitan statistical area (MSA) definitions available as of January 1 of the last year in the dataset. For example, the 2009-2013 table uses vintage geography as of January 1, 2013 including the February 2013 MSA delineation. Vintages for all geographic summary levels are available on the Geography Boundaries by Year page. MSA delineations are available on the Metropolitan and Micropolitan Statistical Areas page.