With the Federal Highway Act of 1954, Congress responded to the recommendations of BPR by appropriating planning funds. BPR was authorized to work with each of the states to develop specific criteria for the parkway and to determine one specific route within each state for the Mississippi River Parkway. By the late 1950s, the familiar green-and-white pilot's wheel marker began to spring up on various sections of the designated route. Planning continued through the 1960s. The 1961 Iowa highway map was the first map in that state to highlight the route.