How many bridges have collapsed in the US?

The FHWA does not maintain a comprehensive count of all bridge collapses, but researchers have documented over 1,500 bridge failures in the United States since 1960. Most are small, local structures. Major highway bridge collapses that cause fatalities are rare but receive significant attention.

What causes bridges to collapse?

The leading causes of bridge collapse in the US are hydraulic factors (scour, flooding) at about 60% of failures, followed by overloading, collision (vehicles or vessels striking the bridge), design or construction defects, and deterioration from deferred maintenance.

Could another major bridge collapse happen?

Yes. While inspection standards have improved dramatically since the 1967 Silver Bridge collapse, the US still has over 42,000 structurally deficient bridges and 18,000 fracture-critical bridges. The risk is managed through inspections and load restrictions, but cannot be fully eliminated without replacing aging infrastructure.

Did the I-35W bridge show signs of problems before it collapsed?

Yes. The I-35W bridge in Minneapolis had been rated structurally deficient since 1990 and received a sufficiency rating of just 50 out of 100. However, it was not scheduled for replacement, only rehabilitation. The collapse in 2007 killed 13 people and injured 145.

Lessons from Major US Bridge Collapses

Silver Bridge, Point Pleasant, WV (1967)

The Silver Bridge was an eyebar-chain suspension bridge carrying US Route 35 over the Ohio River. On December 15, 1967, a single eyebar failed due to a small corrosion-induced crack, causing the entire bridge to collapse in less than a minute. Forty-six people died. The bridge had never received a comprehensive structural inspection in its 39-year life.

The lesson: Bridges need regular, systematic inspections. Congress passed the Federal-Aid Highway Act of 1968, establishing the National Bridge Inspection Standards and creating the National Bridge Inventory. Every public highway bridge in America has been inspected on a regular cycle since then. Every public highway bridge in America has been inspected on a regular cycle since then.

I-35W Mississippi River Bridge, Minneapolis (2007)

The I-35W bridge collapsed during rush hour on August 1, 2007, dropping 111 vehicles into the Mississippi River. Thirteen people were killed and 145 were injured. The bridge was a steel deck truss design carrying 140,000 vehicles per day. It had been rated structurally deficient since 1990.

The NTSB investigation found that original gusset plates were undersized for the loads they carried — a design error from 1961. Additional weight from resurfacing and construction equipment on the bridge at the time of collapse exceeded what the weakened gusset plates could bear.

The lesson: Being classified as structurally deficient does not automatically trigger replacement. The I-35W bridge was in the queue for rehabilitation, not replacement. After the collapse, the FHWA issued guidance for load rating re-evaluations and gusset plate assessments nationwide. Thousands of bridges were re-evaluated.

Francis Scott Key Bridge, Baltimore (2024)

On March 26, 2024, the container ship Dali lost power and struck a pier of the Francis Scott Key Bridge, causing the continuous-truss structure to collapse into the Patapsco River. Six construction workers on the bridge were killed. The bridge was in satisfactory condition with no structural deficiency — this was not a maintenance failure.

The lesson: Bridge vulnerability is not limited to structural condition. Vessel collision, a risk tracked but not always mitigated, can destroy even well-maintained bridges. The collapse renewed national discussion about fracture-critical bridge designs, protective fender systems, and the concentration of infrastructure vulnerability at key chokepoints.

Fern Hollow Bridge, Pittsburgh (2022)

On January 28, 2022, the Fern Hollow Bridge in Pittsburgh collapsed just hours before President Biden was scheduled to visit the city to discuss infrastructure. The bridge had been rated in poor condition for years. Remarkably, there were no fatalities — 10 people were injured.

The lesson: Even bridges that are known to be in poor condition can remain in service for years without repairs due to funding backlogs. Pittsburgh alone has dozens of bridges rated in poor condition. The incident underscored the urgency of the Infrastructure Investment and Jobs Act, signed into law just two months earlier.

Common Patterns Across Collapses

Analyzing the data from bridge failures across the US reveals recurring themes:

Hydraulic failure is the leading cause — Scour and flooding cause approximately 60% of bridge collapses. Water undermines foundations more than any other force.
Redundancy matters — Non-redundant structures like fracture-critical and continuous-truss bridges are more vulnerable to cascading collapse from a single point of failure.
Known problems go unaddressed — Many collapsed bridges had documented issues for years or decades before failure. The gap between identifying a problem and funding its repair is where risk accumulates.
Inspection standards improve after disasters — Each major collapse has led to meaningful regulatory changes, but these changes are reactive rather than preventive.

What Has Improved

The rate of bridge collapses has declined significantly since the 1970s. Regular inspections catch problems earlier. New technologies like structural health monitoring sensors provide real-time data on bridge behavior. Load restrictions on weak bridges prevent overloading. And the ASCE Infrastructure Report Card has raised public awareness of infrastructure needs.

However, the fundamental challenge remains: America has over 42,000 structurally deficient bridges and a repair backlog estimated at $125 billion. Until that gap closes, the risk of preventable failures persists.