"THANKS! (not "First Day"; an " ... " (more);Event" cover) 2-15-1969, Ed Clifton, Conrad Mahnken, Richard Waller & John VanDerwalker occupied underwater lab:"Tektite I", in US Virgin Islands, to research saturated diving. By 3-18-1969 (new world's record) & on 4-15, they surfaced with 58 days of marine research."
"(April 21, 1983) Tacoma Dome opened its door ... " (more)s as the largest wood domed structure in the world. This cover celebrated an "Event" (not "First Day" for a new stamp). The stratospheric balloon stamp (3-31-83) was a recent milestone tied on by the cancel -- Nice Choice! A very handsome item -- Thanks!"
"2-15-1969, Ed Clifton, Conrad Mahnken, Richa ... " (more)rd Waller & John VanDerwalker occupied underwater lab:"Tektite I", in US Virgin Islands, to research saturated diving. By 3-18-1969 (new world's record) & on 4-15, they surfaced with 58 days of marine research. Not a 1st Day cover; an Event cover. THANKS!"