The rapid growth of Philadelphia at the beginning of the 20th century and the associated increase in traffic forced the construction of new roads. The ferry connection between Philadelphia and Camden, which had been in operation until then, was no longer efficient enough.

In order to find an optimal traffic solution for the city, an interstate building commission was set up in 1919. It was headed by Rudolf Modrzejewski. Together with architect Paul Philipp Cret and engineer Leon Moissieff, they came up with an innovative design for a suspension bridge. Its construction began on 6 January 1922 and continued for another 4.5 years. The opening ceremony on 1 July 1926 coincided with the 150th anniversary of the founding of the United States.

At the time of its commissioning, the Benjamin Franklin Bridge, with a main span of 533 m, was the longest suspension bridge in the world. It only enjoyed this title for three years, as Modrzejewski had already broken his own record in 1929 in Detroit (the span of the Ambassador Bridge there is over 560 m long). The total length of the Philadelphia bridge is 2917.86 m, and its scale is also illustrated by the fact that more than 70,000 tonnes of steel were used in its construction. The cables made of it, from which the bridge is suspended, would be the length of the circumference of the globe when the individual wires that make it up are connected. These cables are anchored on both sides of the river in towers clad in granite blocks almost 110 m high. On their sides are reliefs with coats of arms - on the Philadelphia side are the coats of arms of the city of Philadelphia and the state of Pennsylvania, and on the other side are those of the city of Camden and the state of New Jersey. They were designed by sculptor Léon Hermant. The bridge carries seven lanes of traffic (it was originally six lanes and two tramline tracks) and two tracks for underground trains, with pedestrian walkways placed above. The bridge cost $37 million to build. It was the most expensive public investment of those years, but it was also a major financial success and played a significant role in the future economic development of the region. Traffic volumes on the newly opened route proved to be higher than expected, with an estimated 7.8 million cars using it in its first year of operation. Originally known as the Delaware River Bridge, the structure became known as the Benjamin Franklin Bridge in 1955, when the construction of another bridge connecting Philadelphia and New Jersey (the Walt Whitman Bridge) began.

Rudolf Modrzejewski, overseas better known as Ralph Modjeski, was born on 27 January 1861 in Kraków. He was the son of Gustaw Zimajer and the prominent theatre actress Helena Modrzejewska. In 1876, he and his mother emigrated to the United States. Although he showed musical talent already in his youth and received a thorough musical education (he studied piano under Ignacy Jan Paderewski, among others), he ultimately chose a career in engineering. In 1878, he left for Paris to study at the prestigious National School of Roads and Bridges. He graduated from this university in 1885 as the best student of the year. On his return to the United States, he became an assistant in the company of the eminent bridge builder George S. Morison. He worked there in various capacities until 1893, when he opened his own design office in Chicago. In 1924, he entered into a partnership with Frank Masters, who inherited the company after his death. The company still operates today under the name Modjeski & Masters.