Are Customs and Border Protection (CBP) Apprehensions a Reliable Proxy for Undocumented Migration? A Research Note with New Data from Guatemala

Researchers have long relied on United States Customs and Border Protection (CBP) apprehension data as a proxy for undocumented migration, yet the last time their validity was assessed was in 1995. Significant changes in the composition of migrants and border crossings since then raise questions about their continued validity. In this research note, I provide an updated analysis using two independent data sources: the 2018 Guatemalan Census and annual estimates of undocumented Guatemalan arrivals to the United States from The Center for Migration Studies (CMS). Using descriptive and regression analyses, findings show a close alignment between apprehensions, household migrations reported in the Guatemalan census, and Guatemalan arrival estimates. Together, these results indicate that apprehensions remain a reliable indicator of migration flow despite recent changes in migration dynamics along the southern U.S. border.