CPB: https://www.cbp.gov/newsroom/stats/drug-seizure-statistics

USAFacts: https://usafacts.org/answers/how-much-fentanyl-is-seized-at-us-borders/country/united-states/

Grok summary: U.S. Customs and Border Protection (CBP) data shows that in the last fiscal year, approximately 43 pounds (19.5 kilograms) of fentanyl were seized at the U.S.-Canada border. This contrasts sharply with the 21,100 pounds (9,570 kilograms) seized at the U.S.-Mexico border during the same period. This information is supported by several news outlets like CNN, The Globe and Mail, and AP News, which have cited these official figures.