I've known a Heaven like a tent
Traveling tent shows
Circuses and revivals toured America by train in the 1800s, setting up massive canvas tents that could vanish overnight. Dickinson is comparing transcendent experience to a circus.
Silent disappearance
Real circus teardown was loud—hammers, boards, workers shouting. She's describing something that vanishes without physical trace, just empty space where wonder was.
North American detail
Oddly specific geography. She's not talking about abstract heaven but American entertainment culture—the particular way spectacle worked in her time and place.
Bird migration math
Migrating birds leave nothing behind but color traces in the sky. 'Discloses just a hue' means reveals only a tint—the minimum evidence something was there.
Rowing sounds
'Plash' is the specific sound of oars hitting water. The gayety (gaiety) isn't the emotion—it's the bright painted rowboat itself, now gone from sight.