• The Benjamin Franklin Bridge was opened to the public a century ago, on July 1, 1926, just in time for the United States’ Sesquicentennial.

  • Connecting Philadelphia and Camden, it was the longest suspension bridge in the world when it was completed, spanning 1,750 feet.

  • Today, the bridge moves almost 100,000 vehicles each day, and the PATCO High Speed Line, which carries about 20,000 passengers daily.

  • Despite this heavy use and its age, a majority of the bridge is still original – almost every sheet of steel and every rivet.

  • Spanning 100 Years

    How Philadelphia’s monumental bridge was built

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Glancing over the Delaware River, it's hard to think of it separating Pennsylvania and New Jersey. The Benjamin Franklin Bridge not only makes the Delaware passable, but it seemingly narrows the river through its sheer scale and majesty.

Yet for the majority of Philadelphia’s history, the journey across the Delaware – at times fast-rushing, at others frozen over with ice – was far from easy.

Bird's-eye sketch looking west from the Delaware River before the bridge was built.Library Company of Philadelphia

Difficult, and also often unnecessary. During Philadelphia’s early history, the city's commerce and transportation networks were oriented along the waterways rather than across them. The emergence of Camden changed everything.

In 1753, Philadelphia was concentrated to Center City, with only a few settlements dotting the opposite shore.
By the 20th century, not only had Philly expanded, but Camden grew into a thriving industrial city of 120,000 residents, home to businesses like the Campbell Soup and the New York Shipbuilding Companies.

The primary mode of transportation for commuters and commerce between a burgeoning Camden and Philadelphia was via ferry. However, after the turn of the century, the ferry service was becoming increasingly inadequate, especially since automobiles were increasingly entering American life.

In Pennsylvania alone, car registrations jumped from less than half a million in 1920 to about 1.2 million in 1925. In the same period, cars crossing the Delaware via ferry also doubled. Lines of cars would wait for the ferry, stretching city blocks, especially during peak shore season. The situation was becoming untenable.

An article describing overwhelming motorist queues for the ferry on the front page of the Philadelphia Inquirer, July 6, 1925.Inquirer archives

Influential politicians and businesspeople lobbied state and city governments to address the logjam. Combined with the anticipated tourism for the 1926 Sesquicentennial, the Delaware River Bridge Joint Commission (DRBJC) was established in 1917, charged “with the duty of planning and constructing one or more bridges or tunnels,” according to a 1919 DRBJC report.

Up until this point in time, the Delaware only had bridges constructed at narrower points, like those further north in Trenton and Easton. There were bridges across the Schuylkill River too, but the Delaware River at Philadelphia is almost 10 times wider.

Thomas H. Keels, an author and historian specializing in Philadelphia history and architecture, said that “a bridge across the Delaware wasn't technologically feasible until the late 19th century, after the engineering advances made during the construction of the Brooklyn Bridge in the 1880s.”

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The Benjamin Franklin Bridge was designed by Ralph Modjeski of Modjeski and Masters, an engineering firm that still operates out of Mechanicsburg to this day. They’re still involved with maintaining the bridge too, working with the Delaware River Port Authority (DRPA) from an office in Fishtown.

“From an engineering history perspective, it was the first bridge that put all the modern elements of a suspension bridge design together,” said Thomas Murphy, the chief technical officer of Modjeski and Masters.

  • A suspension bridge works in a similar way as a laundry line, but instead of hanging clothes …

  • … the cables support a roadway consisting of more than 22,700 tons of steel and concrete.

  • The cables are locked to giant anchorages on the shores that resist the pull of the cables.

  • The cables run up and over the 380-foot tall towers that hold the cables up just like a pole would hold up a laundry line.

  • The roadway, which sits 135 feet above the water, is hung off the cables by suspenders that come down vertically.

  • Many of the best design concepts at the time were incorporated into the Ben Franklin. Its overall design would later be replicated elsewhere, most notably on the Golden Gate Bridge.

  • Aside from a few parts, most of the bridge is still using the original components installed in the 1920s, a fact made more impressive given how comparatively primitive the tools and techniques were at the time.

    For example, the supporting bases of the towers had to rest on the riverbed, but creating a stable foundation 105 feet underwater was a significant challenge.

    Engineers used a device called a caisson. Derived from the French word for “box,” a caisson functions somewhat like a diving bell. This large cube-like structure was sunk to the riverbed and pressurized, allowing workers to excavate below the waterline in a dry space within.

    This postcard depicts how the foundations of the bridge were built with a caisson, a large cube-like structure made of steel, concrete, and timber.Library Company of Philadelphia

    In similar projects of the era, workers commonly suffered from potentially fatal caisson disease. Now known as decompression sickness, it occurs when a person experiences a sudden decrease in air pressure when leaving a pressurized underwater environment. Remarkably, during the construction of the Benjamin Franklin Bridge, no workers suffered from caisson disease.

    Workers inside the Camden-side underwater caisson.Lehigh University Digital Special Collections

  • Construction started Jan. 6, 1922, with the goal of completing the bridge by the Sesquicentennial on July 4, 1926. However, the project did not have all of its funding secured when construction began, since the bridge was funded by three sources: the City of Philadelphia, and states of New Jersey and Pennsylvania. The staggered nature of the funding actually informed the design of the bridge.

    “If the builders opted for a steel cantilever bridge, they would need to have paid for, essentially, the whole superstructure at once. They just didn't have the money,” said Murphy.

    A suspension bridge allowed sections of the bridge to be built in stages as funds became available. Initially, contracts for just the caissons and demolitions were issued with the available funds, and as additional funding was appropriated later, separate contracts were awarded for other major elements of the bridge.

  • When the caisson was finished, workers finished the tower foundations by installing granite stones, which were quarried and cut to size in Stone Mountain, Ga., then shipped via barge before being lifted onto the pier.

  • After smoothing the exposed granite into a level surface, the base plates and tower legs were installed.

  • The towers were made in sections by Bethlehem Steel and weighed up to 50 tons each. The lower section was set into position with a floating steam-powered crane.

  • Individual tower sections were made from thin steel plates that were joined by hot rivets.

  • Each rivet, a steel pin with a head, was punched through multiple plates while heated. As it cooled, it contracted and tightly clamped the plates together.

  • Riveting was a highly labor-intensive and manual process; Delaware River Port Authority estimates that there are 1.5 million rivets in the entire structure.

  • As the towers were finished, work happened concurrently on the anchorages.

  • Anchorages are massive concrete-filled structures designed to carry the load from the cables.

  • Consulting architect Paul Philippe Cret emphasized the anchorages’ massiveness by using imposing granite blocks.

  • Granite was used because it is a long-lasting stone, unlike sandstone and other alternatives, and serves as weather protection for the interior of the anchorage.

  • Most of the anchorage is protected by blocks that have a rough texture, though the granite’s texture differs at the very base and top of the structure.

  • Cret, who also designed the Rodin Museum, wanted street-level pedestrians and motorists to encounter an anchorage that felt more refined.

  • The granite blocks in these areas are not only smoother in texture but also smaller.

  • The anchorages and the towers were connected with ropes and wires, and a preassembled wooden footbridge was hoisted into position.

  • On Aug. 8, 1924, the first official crossing of the bridge was made by a temporary wooden footbridge.

  • With the footbridge in place, workers could begin assembling the bridge's main cables. The cables were spun from thousands of steel wires, each about the circumference of a pencil.

  • With a giant spool of wire on one side of the anchorage, the wires are passed to the other anchorage via spinning wheels thousands of times.

  • A compacting machine squeezes all of the wires into a solid mass of cable.

  • Permanent cable bands were clamped onto the cables for the suspenders to hang from.

  • With the main cables complete, the weight of the roadway can be supported by suspenders.

  • To keep the weight on the cable distributed evenly, workers add one bit of supporting truss at a time, starting outward from the towers, where cranes were mounted.

  • The incomplete halves of the roadway put an uneven load on the suspension cables. To compensate, the roads are angled slightly skyward.

  • But as the roadway reaches completion, the cables support the structure more evenly and settle into place.

  • When the entirety of the supporting truss is connected to the towers and anchorages, workers drive rivets to connect the individual sections.

  • When the roadway was completed, work began on the surfacing the road. The road surface is one of the parts of the bridge that is regularly replaced due to wear.

  • The original design for the bridge contained street car tracks, which were never put to use. In the 4½ years since the bridge began construction, many local trolleys were converted into buses.

  • Along with pedestrian accommodations, tracks for trains were installed on the exterior of the roadway.

  • The Bridge Line that would use these tracks would come into service in 1936, eventually becoming the PATCO Speedline in 1969.

  • The bridge was officially opened on July 1, 1926, for pedestrians with much pomp and fanfare. The first cars were allowed across the following day.

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  • Aside from a few parts, most of the bridge is still using the original components installed in the 1920s, a fact made more impressive given how comparatively primitive the tools and techniques were at the time.

    For example, the supporting bases of the towers had to rest on the riverbed, but creating a stable foundation 105 feet underwater was a significant challenge.

    Engineers used a device called a caisson. Derived from the French word for “box,” a caisson functions somewhat like a diving bell. This large cube-like structure was sunk to the riverbed and pressurized, allowing workers to excavate below the waterline in a dry space within.

    This postcard depicts how the foundations of the bridge were built with a caisson, a large cube-like structure made of steel, concrete, and timber.Library Company of Philadelphia

    In similar projects of the era, workers commonly suffered from potentially fatal caisson disease. Now known as decompression sickness, it occurs when a person experiences a sudden decrease in air pressure when leaving a pressurized underwater environment. Remarkably, during the construction of the Benjamin Franklin Bridge, no workers suffered from caisson disease.

    Workers inside the Camden-side underwater caisson.Lehigh University Digital Special Collections

  • Construction started Jan. 6, 1922, with the goal of completing the bridge by the Sesquicentennial on July 4, 1926. However, the project did not have all of its funding secured when construction began, since the bridge was funded by three sources: the City of Philadelphia, and states of New Jersey and Pennsylvania. The staggered nature of the funding actually informed the design of the bridge.

    “If the builders opted for a steel cantilever bridge, they would need to have paid for, essentially, the whole superstructure at once. They just didn't have the money,” said Murphy.

    A suspension bridge allowed sections of the bridge to be built in stages as funds became available. Initially, contracts for just the caissons and demolitions were issued with the available funds, and as additional funding was appropriated later, separate contracts were awarded for other major elements of the bridge.

The final cost of the bridge, including the cost of the land that was purchased and the demolition costs, was an estimated $36 million, of which New Jersey paid about 40%, and the state of Pennsylvania and the city of Philadelphia split the other 60% between them.

The bridge carried 2 million vehicles during its first three months of operation, twice the number of the original forecast. With the bridge carrying such volumes of traffic, the ferry service ceased to exist three years after the bridge’s opening.

The sun sets behind the Ben Franklin Bridge, seen from Cooper's Poynt Park on Tuesday, Sept. 30, 2025 in Camden, NJ.

The Ben Franklin Bridge will close to car traffic in July for its anniversary celebration

The exact timing of the closure has not been announced, but the event is scheduled for July 11 with July 12 as a rain date.

With a new transportation corridor between South Jersey and Philadelphia, suburban commuter towns such as Cherry Hill, Haddonfield, and Collingswood experienced a population boom — Camden County gained almost 50,000 new residents between 1920 and 1940.

Beyond Philly’s suburbs, the Ben Franklin also transformed the Jersey Shore. Following the bridge’s opening, the Shore enjoyed a massive real estate boom. “Huge hotels went up in both Atlantic City and Asbury Park. The Jersey Shore becomes the world's playground,” said Keels.

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Since the Benjamin Franklin was completed, the Betsy Ross, Commodore Barry, and Walt Whitman bridges have joined the landscape around Philadelphia. John T. Hanson, CEO of the DRPA, says he loves all four bridges like his kids.

"They're all different, and they're all spectacular in their own way," he said, "but the Ben Franklin has a special place in a lot of people's hearts."

“It's part of the skyline. It's on every news channel, it's always in their background. It's the oldest bridge, it's the first bridge, and many of the people in the region have some connection to it,” said Hanson.

A century after it opened, it continues to connect people as both public infrastructure and a public monument.

“We are building something here that will endure and be at its full usefulness after all present here today are gone,” said Delaware River Bridge Joint Commission member Theodore Boettger on Dec. 12, 1924.

“These walls of concrete and granite are built to last centuries.”

The bridge was later painted “Bicentennial Blue” in 1976 for the nation's 200th birthday.
The bridge was later painted “Bicentennial Blue” in 1976 for the nation's 200th birthday.Visit Philadelphia

Staff Contributors

  • Design, Development, and Reporting: Jasen Lo
  • Additional Design and Development: Sam Morris
  • Videography: Gabe Coffey
  • Editing: Sam Morris
  • 3D Model: Companion 3D via Turbosquid
  • Copy Editing: Scott Sturgis

Acknowledgements & Note

Historical photos provided by the Library Company of Philadelphia and Lehigh University’s Digital Special Collections.

Many thanks to Charles Carswell for The Building of the Delaware River Bridge: Connecting Philadelphia, Pa. and Camden, N.J., and to Maureen Howard and Michael Howard for Benjamin Franklin Bridge.

An earlier version of this story incorrectly stated that PATCO is owned by New Jersey Transit. The story has since been corrected. PATCO is owned by the Delaware River Port Authority.

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