The official name of the I-74 bridge is the Iowa-Illinois Memorial Bridge, in memory of those who served in World War I. When replacement for the 1935 and 1959 spans is built at the end of this decade, the monument will be relocated, reports WQAD.
Pictures of the plaques and the bridge are viewsble at historicbridges.org.
The marker is in the southeast corner of the intersection of 14th Street (the NB I-74 offramp) and State Street (NB US 67). Semi-recent Google Street View images show trees in the park area, but those have recently been taken down, as you can see in the video.