The next time you drive across a bridge, there's a 1-in-13 chance the Federal Highway Administration has flagged it as structurally deficient.
That's not a fringe concern. It's the result of decades of deferred maintenance, shrinking rural tax bases, and infrastructure built to a 50-year lifespan that expired while budgets got cut. The FHWA tracks every one of America's 617,000 public bridges in its National Bridge Inventory — updated annually, publicly available, and almost never talked about.
We pulled the 2022 data and aggregated it to the county level. Here's what we found.
The data
FHWA National Bridge Inventory · 2022 · % bridges rated poor condition
Counties with the most bridges in crisis
617,000
Total U.S. bridges
43,500+
Rated poor condition
7.5%
National average
Source: FHWA NBI 2022. "Poor" = component rating ≤ 4 on 0–9 NBI scale (23 CFR 490.409).
The national average is 7.5% of bridges in poor condition. In Crawford County, Iowa, it's 40%.
That gap is not an anomaly — it's a pattern. Six of the ten worst counties in America are in Iowa, a state that built out thousands of rural bridges during the mid-century farm boom. Those bridges were designed for a 50-year lifespan. That clock ran out a long time ago.
Why Iowa, Pennsylvania, and West Virginia?
Three factors keep showing up in the worst-performing counties:
Farm-boom infrastructure past its design life. Most rural Iowa bridges were built in the 1950s–1970s to service a rapidly mechanizing agricultural economy. They were never intended to last past 2010.
A shrinking tax base covering the same lane-miles. Rural population loss is real. Fewer residents means fewer taxpayers, but the bridges don't get shorter. Counties that have lost 20–30% of their population since 1980 are maintaining the same infrastructure footprint with a fraction of the revenue.
Equipment that outgrew the bridges. Modern combines and grain wagons routinely exceed the rated weight limits of bridges designed for the equipment of a previous era. The bridges flex. Over decades, they crack.
Pennsylvania's problem is different but related — it has the oldest bridge stock in the nation, concentrated in rural counties where state and county funding haven't kept up with the replacement backlog.
What "structurally deficient" actually means
It's worth being precise. "Structurally deficient" does not mean a bridge is about to collapse. It means at least one key structural component — deck, superstructure, substructure, or culvert — has received a condition rating of 4 or below on the FHWA's 0–9 scale.
A rating of 4 means "poor condition — advanced section loss, deterioration, spalling or scour." Bridges at this level are typically posted with lower weight limits, inspected more frequently, and prioritized for repair or replacement funding.
The bridges that do fail catastrophically — like the I-35W collapse in Minneapolis in 2007 — are often not the ones flagged as structurally deficient in advance. They fail for design flaws or inspection gaps that the NBI rating system doesn't fully capture.
The funding picture
The 2021 Infrastructure Investment and Jobs Act included $26.5 billion specifically for bridge repair and replacement — the largest dedicated bridge investment in American history. The money is real and flowing.
But the backlog is also real. FHWA estimates it would cost roughly $125 billion to eliminate the current poor-condition backlog entirely. Even with the new federal investment, most states are triaging: replacing the worst bridges first while dozens more slide from fair to poor condition each year.
What this data can tell you
The NBI is one of the most complete and consistently maintained public infrastructure datasets in the United States. Every bridge is inspected at least every two years. Every inspection is recorded. The data goes back decades.
That means it's possible to answer questions that matter to planners, engineers, and residents:
- Which counties have the most bridges approaching the end of their design life?
- Where is the ratio of poor-to-fair bridges getting worse fastest?
- Which states are making the most progress with IIJA bridge funds?
- How does bridge condition correlate with county income, population trends, and truck traffic?
Those are the kinds of questions we're building toward. If you're working on infrastructure planning and want to dig into the county-level data for your region, reach out — this is exactly what our pipeline is designed for.