The Census Bureau identified a data collection error for the veteran period of military service question on the Spanish versions of the housing unit paper questionnaires in 2020 and 2021. The housing unit Spanish-language paper questionnaires for the American Community Survey and the Puerto Rico Community Survey listed select periods of service in the incorrect order. As a result, a small number of veterans were assigned an incorrect period of military service.

This error was primarily an issue for older veterans who served before the Vietnam War. The mis-ordered categories included two peacetime periods and two wartime periods (Korean War and World War II). Veteran status and service periods after the Vietnam War were not affected.

The error was present in tables B21002 and S2101 in the 2016-2020 ACS 5-year and 2021 ACS 1-year data releases for Puerto Rico. The affected data were suppressed for all Puerto Rico geographies in the 2017-2021 ACS 5-year data products.

The error was also present in the 2016-2020 ACS 5-year Public Use Microdata Sample (PUMS), 2021 ACS 1-year PUMS, and 2017-2021 ACS 5-year PUMS. For data users working with the ACS PUMS files, the error affected the MLP (period of military service) and VPS (period of service recode) variables. Because the collection error was restricted to Spanish language paper questionnaires, the variables are correct for people living in the 50 states and the District of Columbia.