Unofficial. Gulf Coast First Day Cover Group. Chapter #46 of American First Day Cover Society (AFDCS). First Day of Issue Ceremony Invitation (A) to the dedication of Scott #2561 C3 29c District of Columbia Bicentennial Stamp, FDOI, September 7, 1991, Washington, Texas (unofficial city). "...arranged for stamps to be purchased in Washington, D.C. (the first day city) and to be flown to Houston for this special, unofficial first day ceremony in connection with HOUPEX '91 (from unofficial ceremony program)."  Invitation measures 4 1/4" x 5 1/2".