Pittsburgh: The City of Bridges

Aerial view of the North Side, featuring Pittsburgh’s “Three Sister” Bridges, the Sixth, Seventh, and Ninth Street Bridges, Allegheny Conference on Community Development Photographs, Detre Library & Archives at the History Center
Pittsburgh’s “Three Sister” Bridges, the Sixth, Seventh, and Ninth Street Bridges. The “Three Sister” bridges were part of a massive series of bridge-building campaigns begun in 1924 by the Allegheny County Department of Public Works, and finished in the late 1930s by the Depression-period Allegheny County Authority. Credit: Allegheny Conference on Community Development Photographs, Detre Library & Archives at the History Center

Affectionately known as the “City of Bridges,” Pittsburgh boasts 446 bridges – more than any other city in the world, including Venice, Italy. Long before the majestic bridges soared above the Three Rivers, Pittsburgh was a rugged terrain of deep valleys, creeks, and rivers, isolating many of the city’s residents.

When the first European settlers arrived in the 1700s, they had to cross streams and climb steep hillsides just to travel around the region. To overcome these challenges, the settlers built wooden bridges to connect newly constructed roadways and span the rivers and valleys.

The city’s first river crossing bridge, the Monongahela Bridge, was built in 1818 on the site of what is today the Smithfield Street Bridge. The creator of the Brooklyn Bridge, John Roebling, replaced the wooden structure with a new wire rope suspension bridge, after it was destroyed in the Great Fire of 1845. Increasing weight from additional traffic resulted in its closure and replacement with the modern Smithfield Street Bridge, the oldest steel bridge in the United States.

Hot Metal Bridge, April 27, 1887, Frederick T. Gretton Photographs, Detre Library & Archives at the History Center
Hot Metal Bridge, April 27, 1887: Caption on the front of this photograph reads, “Erecting Bridge over Monongahela River connecting Blast furnace with Mill. Jones & Laughlin.” The official name for the bridge is the Monongahela Connecting Railroad Bridge and Hot Metal Bridge. The bridge was used to transport molten iron from the Jones & Laughlin Steel Corporations' Eliza Furnaces to the Bessemer Converters and open hearths of Jones & Laughlin's South Side mills across the river. Credit: Frederick T. Gretton Photographs, Detre Library & Archives at the History Center
Sixth Street Bridge, March 24, 1917, F. Theodore Wagner, Photographs, Detre Library & Archives at the History Center.
Sixth Street Bridge, March 24, 1917: View of the Sixth Street Bridge from the Bessemer Building in downtown Pittsburgh, spanning the Allegheny River with the North Side in the background. The Sixth Street Bridge (1892-1927) was designed by Theodore Cooper and replaced the second Sixth Street Bridge (1859-1892), designed by John A. Roebling. That bridge in turn was replaced by the fourth Sixth Street Bridge, one of the identical “Three Sisters” Bridges (the other two being the Seventh and Ninth Street Bridges). Credit: F. Theodore Wagner, Photographs, Detre Library & Archives at the History Center.
Smithfield Street Bridge, 1894, Jones & Laughlin Steel Corporation Collection Photographs, Detre Library & Archives at the History Center
Smithfield Street Bridge, 1894: The Smithfield Street Bridge, spanning the Monongahela River at Smithfield Street, has undergone many changes, some radical, others merely cosmetic. The first Smithfield Street Bridge crossed the Monongahela River in 1818 and was likely the first bridge across any of the three rivers in the Pittsburgh area. In the great fire of 1845, the wooden bridge fell within ten minutes. The rebuilding began in 1846 by John Augustus Roebling, who went on to design the famous Brooklyn Bridge. Credit: Jones & Laughlin Steel Corporation Collection Photographs, Detre Library & Archives at the History Center
Smithfield Street Bridge, 1949, Allegheny Conference on Community Development Photographs, Detre Library & Archives at the History Center
Smithfield Street Bridge, 1949: The present Smithfield Street Bridge has two lenticular main spans of 360 feet each, the largest ever built in the United States. The downstream half of the bridge is the original. In 1915, the City Architect, Stanley L. Roush, designed the present portals that included grotesques of workmen at the springings of the arches. In 1934, the old wrought-iron floor was replaced with aluminum, greatly lightening the bridge’s dead weight and the iron railings were replaced by plain hollow aluminum railings. Credit: Allegheny Conference on Community Development Photographs, Detre Library & Archives at the History Center

Throughout the 1900s, as the region’s population boomed, Pittsburgh waged a massive road and bridge campaign with the development of the Interstate Highway System. The result was a variety of bridge designs, including suspension, cantilever, and arch, mostly produced from local steel.

Most recognizable is the only trio of identical bridges in the world, the Roberto Clemente, Andy Warhol, and Rachel Carson suspension bridges, which carry traffic across the Allegheny River to Pittsburgh’s North Side. These and the hundreds of other Pittsburgh bridges not only connect our region’s neighborhoods and residents, but add to the city’s unique and beautiful skyline.

Learn more about the bridges of Pittsburgh in the Pittsburgh: A Tradition of Innovation exhibit.

Brady Smith is the director of marketing and communications at the History Center.

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