Pittsburgh’s “Three Sister” Bridges, the Sixth, Seventh, and also Ninth Street Bridges. The “Three Sister” bridges were component of a massive series of bridge-building campaigns begun in 1924 by the Allegheny County room of windy Works, and finished in the so late 1930s through the Depression-period Allegheny county Authority. Credit: Allegheny Conference top top Community breakthrough Photographs, Detre Library & Archives at the background Center

Affectionately recognized as the “City the Bridges,” Pittsburgh boasts 446 bridges – more than any other city in the world, consisting of Venice, Italy. Long before the majestic bridges soared above the three Rivers, Pittsburgh to be a rugged terrain that deep valleys, creeks, and rivers, isolating plenty of of the city’s residents.

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

The city’s very first river crossing bridge, the Monongahela Bridge, was developed in 1818 top top the site of what is this day the Smithfield Street Bridge. The creator the the Brooklyn Bridge, man Roebling, replaced the wooden structure with a brand-new wire rope suspension bridge, after it was destroyed in the an excellent Fire the 1845. Increasing weight from extr traffic resulted in its closure and replacement v the modern Smithfield Street Bridge, the earliest steel bridge in the unified States.

Hot steel Bridge, April 27, 1887: inscription on the former of this picture reads, “Erecting bridge over Monongahela river connecting Blast heater with Mill. Jones & Laughlin.” The main name for the leg is the Monongahela Connecting rail Bridge and Hot metal Bridge. The leg was supplied to transfer molten iron indigenous the Jones & Laughlin steel Corporations" Eliza heating systems to the Bessemer Converters and open hearths the Jones & Laughlin"s south Side mills throughout the river. Credit: Frederick T. Gretton Photographs, Detre Library & Archives at the background Center
Sixth Street Bridge, march 24, 1917: see of the sixth Street bridge from the Bessemer structure in downtown Pittsburgh, extending the Allegheny River through the North next in the background. The 6th Street bridge (1892-1927) was designed through Theodore Cooper and also replaced the second Sixth Street leg (1859-1892), design by john A. Roebling. The bridge consequently was replaced by the fourth Sixth Street Bridge, among the the same “Three Sisters” Bridges (the 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, extending the Monongahela flow at Smithfield Street, has actually undergone plenty of changes, some radical, others simply cosmetic. The very first Smithfield Street bridge crossed the Monongahela river in 1818 and also was most likely the very first bridge throughout any of the 3 rivers in the Pittsburgh area. In the great fire the 1845, the wood bridge fell within ten minutes. The rebuilding began in 1846 by john Augustus Roebling, who went on to design the well known Brooklyn Bridge. Credit: Jones & Laughlin stole Corporation arsenal Photographs, Detre Library & Archives at the background Center
Smithfield Street Bridge, 1949: The current Smithfield Street Bridge has two lenticular main spans the 360 feet each, the largest ever constructed in the joined States. The downstream half of the bridge is the original. In 1915, the City Architect, Stanley L. Roush, draft the existing portals that consisted of grotesques of workmen at the springings of the arches. In 1934, the old wrought-iron floor was replaced with aluminum, considerably lightening the bridge’s dead weight and the iron railings were replaced by plain hollow aluminum railings. Credit: Allegheny Conference top top Community breakthrough Photographs, Detre Library & Archives at the history Center

Throughout the 1900s, as the region’s populace boomed, Pittsburgh waged a huge road and bridge campaign with the development of the federal government Highway System. The an outcome was a range of bridge designs, consisting of suspension, cantilever, and arch, mostly developed from local steel.

Most recognizable is the just trio of identical bridges in the world, the Roberto Clemente, Andy Warhol, and Rachel Carson suspension bridges, which carry traffic throughout the Allegheny river to Pittsburgh’s phibìc Side. These and also the numerous other Pittsburgh bridges not only connect our region’s neighborhoods and also residents, but include to the city’s unique and beautiful skyline.

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