Minneopa Falls Bridge
The keystone has a date of what appears to be 1879. Here's a zoomed in picture of it.
My mistake, somehow I managed to select the wrong design. It is indeed an open spandrel design, and looks very similar to the original bridge. I'll try to take some pictures of the new bridge soon.
This bridge has been replaced and opened on October 15th. I'll try to post some new pictures next time I visit home. Here's some pictures from the demolition, as well as a link to a local news story showing Governor Quinn visiting the bridge.