As Chicago grew into a center of industry and commerce in the late 19th century, numerous fixed-span crossings were replaced by center-pier swing bridges, the most common type of bridge that allowed pedestrians and wagons to cross the Chicago River while also periodically allowing ship traffic below.
As Chicago developed into a hub of manufacturing and trade in the late 19th century, numerous fixed-arch crossings were replaced by center-pier swing bridges, the most prevalent type of bridge that enabled pedestrians and carts to cross the Chicago River while also occasionally allowing vessel traffic below.