Nationally and Exceptionally Significant Features of the Federal Interstate Highway System

Hernando DeSoto Bridge (Shelby County, Tennessee)
Built 1973
Two-span steel through arch bridge over the Mississippi River on I-40 at Memphis
Open to traffic

I-25 Nogal Canyon Bridge (Socorro County, New Mexico)
Built 1968
Parallel deck truss bridges over Nogal Canyon on I-25
Open to traffic

Mackinac Bridge (Emmet County, Michigan)
Opened Nov. 1, 1957
Suspension bridge over the Straits of Mackinac on I-75 at Mackinaw City
Open to traffic

Memphis & Arkansas Bridge (Shelby County, Tennessee)
Construction began 1945, opened to traffic December 19, 1949 ; Refurbished 1984
Cantilevered through truss bridge over the Mississippi River on I-55 at Memphis
Open to four lanes of traffic