US-421 over Mills Branch
Harlan County, Kentucky · rated Poor in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- US-421 over Mills Branch in Harlan County, Kentucky, is rated in poor condition in the 2025 National Bridge Inventory (as of ).
- It was built in 1934, making it 91 years old at the 2025 inventory.
- It carries about 1,251 vehicles a day (traffic count year 2023).
- Its listed owner is the state highway agency.
- A poor rating means at least one major component - deck, superstructure, or substructure - is rated 4 or lower on FHWA's 0-9 scale. It does not by itself mean the bridge is unsafe; bridges judged unsafe are closed or load-restricted by their owners.
View this bridge on a map → (36.765, -83.15056)
Component ratings
| Component | Rating (2025) | FHWA scale meaning |
|---|---|---|
| Culvert | 4 | Poor condition |
Bridge details
| Structure | Concrete culvert |
| Length | about 20 ft |
| Location | 1.0 Mi East of Jct Ky 568 |
| NBI structure number | 048B00024N |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Kentucky department of transportation.
All bridges nearby: Harlan County, KY bridge conditions · Kentucky bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.