Bridge conditions in Boone County, Illinois
109 inventoried bridges · 11 rated poor · 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
Of the 109 Boone County bridges in the federal inventory, 11 carry a poor rating. That 10.1% share is roughly 2x the national average.
- 11 of the 109 bridges in Boone County, Illinois, are rated in poor condition (10.1%) in the 2025 National Bridge Inventory, as of .
- 45 bridges (41.3%) are rated good and 53 (48.6%) fair.
- The median Boone County bridge was built in 1986.
- The busiest poor-rated bridge is S. Appleton Road over Kishwaukee River (built 1964), carrying about 11,700 vehicles a day.
Good 41.3% · Fair 48.6% · Poor 10.1% of 109 bridges
Bridges rated poor
Every bridge in the county with a poor rating, busiest first. Poor means a major component is rated 4 or lower on FHWA's 0-9 scale; it is a repair flag, not a closure notice.
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| S. Appleton Road over Kishwaukee River | 1964 | 11,700 | Poor |
| Lawrenceville Road over Piscasaw Creek | 1974 | 2,050 | Poor |
| Stone Quarry Rd over Hackey Creek | 1945 | 1,550 | Poor |
| Edson Road over Beaver CR | 1973 | 700 | Poor |
| County Line Rd over Mud Creek | 1959 | 675 | Poor |
| Wheeler Rd over Cn RR | 1998 | 200 | Poor |
| Capron Rd over Piscasaw Creek | 1958 | 150 | Poor |
| Huber Road over Mosquito Creek | 1977 | 150 | Poor |
| Capron Rd over Br Piscasaw Creek | 1981 | 150 | Poor |
| Mill Rd over Piscasaw Creek | 1975 | 125 | Poor |
| Denny Road over Piscasaw Creek | 1977 | 50 | Poor |
Busiest bridges in the county
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| I 90 over Stream | 2014 | 51,100 | Fair |
| I-90 over Stream | 1958 | 28,000 | Good |
| I 90 WB over Mosquito Crk | 2013 | 28,000 | Fair |
| I 90 EB over Mosquito Ckr | 2013 | 28,000 | Good |
| I-90 over Stream | 1958 | 25,700 | Fair |
| I-90 over Stream | 1958 | 25,550 | Good |
| US 20 EB over I-90 | 1964 | 14,200 | Fair |
| US 20 WB over I-90 | 1958 | 14,200 | Fair |
| US 20 WB over S Appleton Rd | 1966 | 13,700 | Fair |
| US 20 Br over Beaver Creek | 1957 | 13,400 | Fair |
Source: FHWA National Bridge Inventory, 2025. Counts cover inventoried highway bridges over 20 feet; ratings are reported by the state DOT.
All of Illinois: Illinois bridge conditions by county · every download on the data page.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.