The Sixth Street Bridge that we see today is not the original Sixth Street Bridge. In 1859, the first Sixth Street Bridge was built by John Roebling which built this bridge as his third and final bridge in Pittsburgh. The original bridge had two main spans of 344 feet (105 m) with shore spans of 177 and 171 feet (54 and 52 m). The floors were suspended from wire hangers that were then suspended from wire catenaries. Eventually, due to electric streetcars, heavy loads, and more traffic, the bridge demanded to be wider and much more rigid so it came down in 1892.
In 1892, the second Sixth Street Bridge was built by an engineer named Theodore Cooper for the Union Bridge Company. The main spans were 440 feet (130 m) long, each having through trusses of the camel-back type with upward-angled upper chords, and were twice as wide as the previous bridge. In 1927 the bridge had to be taken apart because the steelwork was too brittle for safety. So in 1927, the main spans were somewhat trimmed down temporarily from their 80-foot (24 m) height which were then lowered onto barges and floated down the Ohio river to the back channel of Neville Island to become part of the Coraopolis Bridge. Finally in 1994 the steel was scrapped. 
The Sixth Street Bridge's piers were built with arched openings beneath the river bed in order to accommodate future subway tunnels, following the recommendation of transportation planner Bion J. Arnold. The North Shore Connector tunnels completed in 2012 did not make use of this provision, but were bored further west (downstream) and do not pass beneath the bridge.
The bridge was renamed on August 6, 1998, as part of a compromise after the Pirates sold the naming rights to PNC Park to locally-based PNC Financial Services. Before the naming rights were sold, there was hugely popular sentiment in Pittsburgh to name the park itself after Clemente.
It is closed to vehicular traffic on Pirates' and Steelers' game days, providing a pedestrian route to PNC Park and Heinz Field. When PNC Park was built, a statue of Roberto Clemente, originally erected at Three Rivers Stadium, was placed at the southeast corner of the park, right at the north anchorage of the Roberto Clemente Bridge.
The Pittsburgh History and Landmarks Foundation in cooperation with the Riverlife Task Force, the City of Pittsburgh, and Duquesne Light Company, funded and managed the architectural lighting of the bridge. On November 20, 2002, the bridge was lit for the first time.
Plaque on the North Shore of the Sixth Street Bridge.