Ever wonder why there’s more vacant land than normal just west of Union Station? It was the planned route for an interstate that would have looped around downtown, cutting Lafayette Square off from downtown (even more) and creating a noose around the area.
One of the relics of this aborted interstate are the ramps from Pine onto Highway 40, and other bits of excess concrete such as the giant interchange of I-55 and I-44. You can read my original post about the interstate here.
The Truman Parkway was an attempt at creating the connections that the lower portion of the interstate would have provided.