41 people on the Terrorist Screening Database were encountered at the southern border from Oct. 1, 2017, to March 31, 2018, but 35 of them were U.S. citizens or lawful permanent residents. Six were classified as non-U.S. persons.
On the northern border, CBP stopped 91 people listed in the database, including 41 who were not American citizens or residents.
Remember Sen Ted Kennedy was on the Terrorist Watch list and couldn't get off.
To summarize: 41 folks on the Terrorist Screening Database were stopped at the southern border. 85% of them were determined NOT to be terrorists, it does NOT say the remaining 15% migrants were determined to be terrorists. IF we use N=41, that is <1% of the "4000 terrorists stopped at the southern border" the WH claims.
Extra Credit: Those stopped on the southern border for mismatches on the TSD is less than half of those stopped at the Northern Border. Shouldn't we be building a Northern Wall? Eh?