Michigan Avenue Bridge

The Michigan Avenue Bridge (officially DuSable Bridge) is a bascule bridge that carries Michigan Avenue across the main stem of the Chicago River in downtown Chicago, Illinois, United States

The bridge was proposed in the early 20th century as part of a plan to
link Chicago's south side and north side parks with a grand boulevard. Construction of the bridge started in 1918, it opened to traffic in 1920, and work on the decoration of the bridge was completed in 1928

The bridge provides passage for vehicles and pedestrians on two levels; it is an example of a fixed trunnion bascule bridge, which later became widely known as a "Chicago style bascule". The bridge is included in the Michigan–Wacker Historic District and has been designated as a Chicago Landmark.

The Michigan Avenue Bridge has a north–south orientation, spanning the main stem of the Chicago River between the Near North Side and Loop community areas of Chicago.Its northern portal lies at the foot of the Magnificent Mile, between the Wrigley Building and Tribune Tower. Its southern portal is at the intersection of Michigan Avenue and Wacker Drive, overlooked by the London Guarantee Building and 333 North Michigan. The neighboring bridges are Columbus Drive Bridge to the east and Wabash Avenue Bridge to the west.

The bridge is situated in a historically significant area.The northern end of the bridge covers part of the Jean Baptiste Point Du Sable Homesite. The site is commemorated by a National Historic plaque in Pioneer Court, together with other commemorations of the history of the area. The southern half of the bridge passes over the site of Fort Dearborn, which was constructed in 1803. The Fort is commemorated by a large relief above the entrance of the London Guarantee Building, and brass markers positioned in the sidewalks on the south side of the bridge delineate the posited outline of the original blockhouse of the fort.

The historical significance of the location has been used as the basis for a number of proposals to rename the bridge. In 1921 the Chicago Historical Society suggested that the bridge should be named Marquette–Joliet Bridge, and in 1939 it was proposed to rename the bridge as Fort Dearborn Bridge. These proposals were not adopted.

In October 2010, the bridge was renamed DuSable Bridge in honor of Jean Baptiste Point du Sable Chicago's first permanent resident. A fur trader who married into the Potawatomi tribe of native Americans, he opened a trading post and established a permanent homestead near the mouth of the Chicago River in the 1780s

A boulevard to link the parks on Chicago's north and south sides was proposed as early as 1891. An early plan called for a tunnel to link Michigan Avenue south of the river with Pine Street (now Michigan Avenue) north of the river. In 1903 an editorial in the Chicago Tribune proposed a new bascule bridge across the river at Michigan Avenue

Michigan Avenue Bridge is a double-leaf, double-deck, fixed counterweight, trunnion bascule bridge. It was engineered by the Chicago Department of Public Works, Bureau of Engineering; Edward H. Bennett was the consulting architect and William A. Mulcahy the chief engineer of construction.

Each of the bridge's leaves are divided into two along the axis of the bridge such that it functions as two parallel bridges that can be operated independently of one another; at the time of construction bridges in the Chicago River were frequently struck by vessels, and this duplex arrangement allows for leaves damaged in such a collision to be opened for repair without needing to completely close the bridge to traffic.

The bridge abutments and the facing of the bridge tender houses are made of Bedford stone. There are four bridge tender houses: the northwest and southeast bridgehouses house the controls for operating the bridge; the northeast and southwest bridgehouses are purely decorative