Why So Much Fentanyl Is Being Seized at the Border

MEXICO CITY—Fentanyl seizures at the United States-Mexico border more than doubled in 2021 to surpass heroin for the first time ever. But experts say the COVID-19 border shutdown may explain the record numbers because it gave agents more time to inspect fewer vehicles. 

U.S. Customs and Border Protection (CBP) statistics showed that 10,586 pounds of fentanyl and 4,969 pounds of heroin were seized on the southern U.S. border during the 2021 fiscal year. The total for fentanyl was more than double the amount for the same period in 2020 and it was...