From A City Plan for St. Louis (1907). The top image depicts the southern terminus of Kingshighway, near Caldwell Street, along the Mississippi River. The lower image is Kingshighway as it looked along Forest Park (on the left) with its characteristic boulevard landscaping already in place by 1907. The absence of gridlock, dozens of traffic signals, and the skyline of the Barnes-Jewish Hospital is stark.
A few interesting points about the image at top: first, Kingshighway Boulevard no longer exists at this location. The initial plan for the city suggested that Kingshighway would extend from its current roadway, then jog southeast at what is now Bellerive Boulevard. Bellerive for many years was known as Kingshighway South, or some variant of that name. However, with the building of Interstate 55 and other issues, the linking of Bellerive as an integral portion of Kingshighway faltered and then disappeared.