No, they don't...? https://www.cbp.gov/border-security/ports-entry/operations/preclearance https://www.cbp.gov/border-security/ports-entry/operations/p... And

No, they don't...? https://www.cbp.gov/border-security/ports-entry/operations/preclearance https://www.cbp.gov/border-security/ports-entry/operations/p... And the bizarreness is that they're simultaneously trusting them enough to handle immigration, but not trusting them enough to handle passenger screening.