GREENVILLE, S.C. (September 10, 2022) – This Sunday, Sept. 11, marks the 21-year anniversary of the 9/11 terrorist attacks on the World Trade Center in New York City, the Pentagon and United Airlines Flight 93 which crashed in suburban Pennsylvania. Patriot Day serves as a remembrance of the lives lost on that September morning. Flags will be flown at half-staff for the entire day on September 11.