I found a folder on my old computer with some photos I took while in Minnesota back in 2015 (my first year traveling with Airbnb). I will be posting more photos from previous trips once I get back to Durham but for now here is one I referred to the other day when I posted photos of this large bridge in Duluth, Minnesota.
The lower portion raises straight up (possibly as far up so the top of it goes partially in to the bottom of the top portion – got all that??) depending on how tall the ship wanting to pass underneath it is.