"The FBI’s Terrorist Screening Database is the U.S. government’s primary watch list, and what people usually mean when they refer to the terrorist watch list. It contains about 1 million records. About 5,000 of those records — 0.5 percent — are about Americans."
"As of 2017, there were about 1.16 million people on the TSDB; the great majority are foreigners, but the list also includes approximately 4,600 U.S. persons." [1]