Again, just in case it is of interest to others, here is a list of all irregular exchange closures back at least to 1954, according to Norgate:
https://norgatedata.com/data-content-tables.php#futures
NYSE - Irregular Exchange Closures
Day Date Reason
Fri Dec 24, 1954 Christmas Eve
Mon Dec 24, 1956 Christmas Eve
Fri Dec 26, 1958 Day after Christmas
Mon May 29, 1961 Day before Decoration Day
Mon Nov 25, 1963 Funeral of President John F. Kennedy
Fri Dec 24, 1965 Christmas Eve
Mon Feb 12, 1968 Lincoln's Birthday
Tue Apr 9, 1968 National Day of Mourning for Martin Luther King, Jr.
Various Jun 12-Dec 31, 1968 4-day week - "Paperwork Crisis"
Mon Feb 10, 1969 Heavy snow
Mon Mar 31, 1969 Funeral of former President Dwight D. Eisenhower
Mon July 21, 1969 National Day of Participation for the lunar exploration
Thu Dec 28, 1972 Funeral of former President Harry S. Truman
Thu Jan 25, 1973 Funeral of former President Lyndon B. Johnson
Thu Jul 14, 1977 Blackout in New York City
Fri Sep 27, 1985 Hurricane Gloria
Wed Apr 27, 1994 Funeral of former President Richard M. Nixon
Tue-Fri Sep 11-14, 2001 Terrorist attack on World Trade Center
Fri Jun 11, 2004 National Day of Mourning for former President Ronald W. Reagan
Tue Jan 2, 2007 National Day of Mourning for former President Gerald R. Ford
Mon-Tue Oct 29-30, 2012 Hurricane Sandy
Wed Dec 5, 2018 Funeral of former President George H.W. Bush