The Oldest Bridges in America Still Carrying Traffic

Bridges Over 100 Years Old

The NBI contains over 17,000 bridges built before 1925 — meaning they are now at least a century old. These structures are concentrated in the Northeast and Midwest, where road infrastructure developed earliest. Stone arch bridges, iron truss bridges, and early concrete structures make up the bulk of this inventory.

Remarkably, many of these centenarian bridges maintain respectable condition ratings. Stone and masonry arch bridges, in particular, age gracefully. The compressive forces in an arch are naturally suited to stone and concrete, materials that gain strength under compression. The arch design distributes loads so effectively that some Roman bridges are still standing after two millennia.

Where the Oldest Bridges Are

States with the oldest bridge inventories reflect the pattern of American settlement and infrastructure development:

• Pennsylvania — Home to more pre-1900 bridges than any other state, including stone arch bridges on turnpike routes and iron truss bridges over mountain streams. See our Pennsylvania bridge data.
• New York — From Erie Canal-era stone bridges to early 20th century steel structures in New York City, the state has a deep history of bridge building.
• Massachusetts — Colonial-era stone bridges on original post roads, plus early industrial-era iron and steel bridges.
• Ohio — A large inventory of 19th-century iron truss bridges, many built for the National Road and early state highway system.
• Vermont — Famous for its covered bridges, several dating to the early 1800s.

You can explore the oldest bridges in each state on our oldest bridges ranking.

Age and Condition: The Data

The relationship between bridge age and condition is clear but not absolute. NBI data shows that bridges over 50 years old are roughly twice as likely to be rated structurally deficient compared to bridges under 30. However, age is not destiny — maintenance quality, original construction materials, traffic levels, and climate all play critical roles.

Some of the oldest bridges in the NBI maintain A and B grades because they were built with durable materials, carry light traffic, and receive consistent maintenance. Conversely, some bridges barely 30 years old have already deteriorated to D and F grades due to construction defects, heavy truck traffic, or neglected maintenance.

The Design Life Question

Modern bridges are designed for a 75-year service life under the AASHTO bridge design specifications. Before the mid-20th century, bridges were typically designed for shorter service lives with lower traffic loads. The fact that many pre-1925 bridges continue to function is a testament to conservative engineering and overbuilding common in that era.

However, these old bridges often cannot safely carry modern traffic loads. Many are load-posted with weight restrictions that prohibit heavy trucks. Others are functionally obsolete due to narrow lanes, low clearance, or inadequate guardrails.

Historic Preservation Challenges

Many of America's oldest bridges are listed on the National Register of Historic Places or are eligible for listing. This creates a tension between safety upgrades and historic preservation. Widening, strengthening, or replacing a historic bridge can trigger complex regulatory review under Section 106 of the National Historic Preservation Act.

Some states have developed innovative approaches that preserve historic character while addressing safety: steel reinforcement hidden inside masonry arches, modern guardrails designed to match historic aesthetics, and parallel structures that carry heavy traffic alongside preserved historic bridges limited to light vehicles.