That statistic (more trees than 100 years ago) is less impressive when you consider the baseline (1920's) had already clear-cut most of the old/ancient forests

That statistic (more trees than 100 years ago) is less impressive when you consider the baseline (1920's) had already clear-cut most of the old/ancient forests in the USA (hence the conservationist movement decades prior) during the gilded age. This is why almost all of the Appalachian Mountains and east coast are only newer-growth forests. A better measure would be comparing current forest size to pre-European colonization of Americas, if it were possible.