I'm very familiar with all 4 of the United States varieties, because they all grow in the same basic area.

One thing about tree height is it's very dependent on the height of the trees around it. A giant sequoia will grow extremely wide and short if it's not surrounded. So it makes sense that the height records would be old, because if it's surrounded by other older and taller trees it'll be forced to grow even taller. In a feedback loop that last hundreds or thousands of years.

charismatic megaflora

Great article. Very stout.