This is actually two bridges, one bridge is of 1940 vintage (upstream), the other bridge is of 1988 vintage. While they look the same, the older upstream bridge is narrower. Beyond that, they have the same footprint.

In visiting this area, I was curious why two such small towns as Natchez, Mississippi, and Vidalia, Louisiana, could justify not just one but two huge bridges across the Mississippi River. The City of Vidalia web site clears up the issue noting that over 2-million people live within 200-miles of the twin spans, and the bridges carry nearly 30,000 vehicles per day on average.