The Robert Street Bridge is a reinforced concrete multiple-arch bridge that spans the Mississippi River

Mississippi River

The Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains...

 in downtown St. Paul

Saint Paul, Minnesota

Saint Paul is the capital and second-most populous city of the U.S. state of Minnesota. The city lies mostly on the east bank of the Mississippi River in the area surrounding its point of confluence with the Minnesota River, and adjoins Minneapolis, the state's largest city...

, Minnesota. The bridge is notable for its complex design that was required to accommodate river traffic, the St. Paul Union Pacific Vertical-lift Rail Bridge

St. Paul Union Pacific Vertical-lift Rail Bridge

The St. Paul Union Pacific Vertical-lift Rail Bridge is a vertical-lift bridge that spans the Mississippi River in downtown St. Paul, Minnesota. This is one of only three vertical-lift bridges along the Mississippi River, along with the Hastings Rail Bridge in Hastings, Minnesota and the Wabash...

 crossing underneath it at an angle, and roadways on the downtown side of St. Paul. The bridge is also notable for a monumental reinforced concrete rainbow arch. The rainbow arch not only provides 62 feet of headroom above the river, but also provides a strong aesthetic focus. It was built in 1924-1926 by Fegles Construction Company, Ltd. and designed by Toltz, King & Day, Inc. The bridge was added to the National Register of Historic Places

National Register of Historic Places

The National Register of Historic Places is the United States government's official list of districts, sites, buildings, structures, and objects deemed worthy of preservation...

 in 1989.

The bridge was commissioned in the early 1920s to replace a wrought-iron span, originally built in 1884-1885, that had become obsolete due to increasing traffic. The engineers who designed the bridge had several obstacles to work around. The tracks of the Chicago, St. Paul, Minneapolis and Omaha Railway

Chicago, St. Paul, Minneapolis and Omaha Railway

The Chicago, St. Paul, Minneapolis and Omaha Railway or Omaha Road was a railroad in the U.S. states of Nebraska, Iowa, Minnesota, Wisconsin and South Dakota. It was incorporated in 1880 as a consolidation of the Chicago, St. Paul and Minneapolis Railway and the North Wisconsin Railway,. The...

, St. Paul Union Depot, and the Chicago Great Western Railway

Chicago Great Western Railway

The Chicago Great Western Railway was a Class I railroad that linked Chicago, Minneapolis, Omaha, and Kansas City. It was founded by Alpheus Beede Stickney in 1885 as a regional line between St. Paul and the Iowa state line called the Minnesota and Northwestern Railroad...

 mainline were factors. The engineers also had to provide adequate clearance above the river, as defined by the United States War Department at the time. Finally, the bridge had to clear Second Street in downtown St. Paul and work through a busy manufacturing district at the south end. The location of nearly every pier was dictated by these requirements. As a result, the bridge was designed with a combination of barrel-arch and rib-arch flanking spans and a rainbow arch for the central span.

One of the members of the crew building the bridge was Warren Burger, future Chief Justice of the United States

Chief Justice of the United States

The Chief Justice of the United States is the head of the United States federal court system and the chief judge of the Supreme Court of the United States. The Chief Justice is one of nine Supreme Court justices; the other eight are the Associate Justices of the Supreme Court of the United States...

.