Pittsburgh’s “Three Sister” Bridges, the Sixth, Seventh, and also Ninth Street Bridges. The “Three Sister” bridges were component of a massive collection of bridge-building campaigns started in 1924 by the Allegheny County department of publicly Works, and also finished in the late 1930s through the Depression-period Allegheny county Authority. Credit: Allegheny Conference on Community advancement Photographs, Detre Library & Archives in ~ the background Center

Affectionately well-known as the “City the Bridges,” Pittsburgh boasts 446 bridges – more than any kind of other city in the world, consisting of Venice, Italy. Long before the majestic bridges soared over the three Rivers, Pittsburgh was a rough terrain of deep valleys, creeks, and rivers, isolating plenty of of the city’s residents.

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When the an initial European settlers arrived in the 1700s, they had to overcome streams and climb steep hillsides simply to travel about the region. To conquer these challenges, the settlers constructed wooden bridges to connect newly constructed roadways and also span the rivers and also valleys.

The city’s first river crossing bridge, the Monongahela Bridge, was built in 1818 top top the website of what is today the Smithfield Street Bridge. The creator that the Brooklyn Bridge, john Roebling, replaced the wooden structure with a new wire rope suspension bridge, after it was ruined in the good Fire that 1845. Raising weight from extr traffic brought about its closure and also replacement with the contemporary Smithfield Street Bridge, the oldest steel bridge in the united States.

Hot metal Bridge, April 27, 1887: caption on the prior of this photo reads, “Erecting bridge over Monongahela flow connecting Blast furnace with Mill. Jones & Laughlin.” The main name for the bridge is the Monongahela Connecting rail Bridge and also Hot steel Bridge. The bridge was offered to transport molten iron from the Jones & Laughlin stole Corporations" Eliza furnaces to the Bessemer Converters and open hearths that Jones & Laughlin"s southern Side mills throughout the river. Credit: Frederick T. Gretton Photographs, Detre Library & Archives in ~ the background Center
Sixth Street Bridge, march 24, 1917: see of the 6th Street bridge from the Bessemer structure in downtown Pittsburgh, extending the Allegheny River through the North next in the background. The 6th Street leg (1892-1927) was designed through Theodore Cooper and also replaced the second Sixth Street bridge (1859-1892), designed by man A. Roebling. The bridge subsequently was changed by the fourth Sixth Street Bridge, among the identical “Three Sisters” Bridges (the various other two being the Seventh and Ninth Street Bridges). Credit: F. Theodore Wagner, Photographs, Detre Library & Archives in ~ the history Center.
Smithfield Street Bridge, 1894: The Smithfield Street Bridge, covering the Monongahela flow at Smithfield Street, has undergone plenty of changes, part radical, others merely cosmetic. The very first Smithfield Street leg crossed the Monongahela river in 1818 and also was likely the an initial bridge throughout any of the three rivers in the Pittsburgh area. In the an excellent fire the 1845, the wooden bridge fell within ten minutes. The rebuilding started in 1846 by john Augustus Roebling, that went on to architecture the famed Brooklyn Bridge. Credit: Jones & Laughlin stole Corporation repertoire Photographs, Detre Library & Archives at the background Center
Smithfield Street Bridge, 1949: The present Smithfield Street Bridge has actually two lenticular key spans of 360 feet each, the largest ever built in the unified States. The downstream half of the leg is the original. In 1915, the City Architect, Stanley L. Roush, designed the current portals that contained grotesques the workmen in ~ the springings of the arches. In 1934, the old wrought-iron floor was replaced with aluminum, significantly lightening the bridge’s dead weight and also the iron railings were changed by plain hollow aluminum railings. Credit: Allegheny Conference on Community advancement Photographs, Detre Library & Archives in ~ the background Center

Throughout the 1900s, as the region’s population boomed, Pittsburgh waged a substantial road and also bridge campaign with the breakthrough of the interstate Highway System. The result was a variety of bridge designs, including suspension, cantilever, and arch, mostly produced from regional steel.

Most recognizable is the just trio of the same bridges in the world, the Roberto Clemente, Andy Warhol, and also Rachel Carson suspension bridges, which bring traffic throughout the Allegheny river to Pittsburgh’s phibìc Side. These and the numerous other Pittsburgh bridges no only attach our region’s neighborhoods and also residents, but add to the city’s unique and also beautiful skyline.

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Learn more about the bridges the Pittsburgh in the Pittsburgh: A heritage of development exhibit.