>>1848409The bridge was built in the 1920s. the area's "chain of rocks" rapids were silenced with a low water level dam installed in the 1950s.
The bridge has a bend so that riverboat captains could safely pass through. it looks unecessary because the rapids aren't big anymore.
The Old Chain of Rocks bridge is still open for foot and bicycle traffic and is part of St Louis' Mississippi Greenway trail system.