Here's a nice early view of the mill on Tom Sawyer's Island (er...it IS Harper's Mill, isn't it?), taken from the Mark Twain. You can see the shadow of one of the smokestacks (or whatever they're called, since smoke doesn't come out of them)! It's a beautiful, sunny day, not a cloud in the sky. Folks are already exploring their brains out, mom is leading the way in the foreground. One thing that occurs to me is that, even though this mill can't be more than one or two years old, they've managed to somehow age the wood so that it looks like it has been there for many years. How?
I love the stuff in the distance, the Fort, the Keel Boat, and the Train. While the slide is undated, the foliage is pretty sparse out there...I'm guessing that this is around 1957.