> Maybe the decline in American museums has been going on quite a while.
It may also be due to large improvements at museums being a very sporadic occurrence. I remember growing up, my local museum (the Buffalo Museum of Science) feeling very dated, and when we visited Toronto, the Ontario Science Centre felt very new and fresh. But now the Buffalo museum has had some recent upgrades and feels new, whereas the last time I was at the Ontario Science Centre, it felt like I was seeing the same exhibits I saw as a kid 30 years earlier. Perhaps when my kids are grown, it will have reversed again.