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Bridge conditions in Mason County, Illinois

86 inventoried bridges · 3 rated poor · 2025 National Bridge Inventory

United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled August 20, 2026

3 of the 86 bridges the federal inventory lists in Mason County are rated poor; the rest split 31 good and 52 fair.

3 of the 86 bridges in Mason County, Illinois, are rated in poor condition (3.5%) in the 2025 National Bridge Inventory, as of August 20, 2026.
31 bridges (36.0%) are rated good and 52 (60.5%) fair.
The median Mason County bridge was built in 1983.
The busiest poor-rated bridge is Tr 190 over Main Ditch (built 1972), carrying about 50 vehicles a day.

Good 36.0% · Fair 60.5% · Poor 3.5% of 86 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
Tr 190 over Main Ditch	1972	50	Poor
Tr 153 over Killion Ditch	1972	25	Poor
Tr 208 over Sleepy Hollow Ditch	1986	25	Poor

Busiest bridges in the county

Bridge	Built	Vehicles/day	Condition
US 136 / Il 29 over Main Ditch	1958	2,500	Fair
Ill 29 over Allens Grove Ditch	1959	2,450	Good
Fap 614 (il 78) over Ditch	1978	2,250	Fair
Il 29 over Sleepy Hollow Ditch	1959	2,000	Fair
Il 29 over Salt Creek	2002	2,000	Fair
Ill 78 over White Oak Creek	1931	1,750	Fair
US 136 over Ditch	1966	1,700	Fair
Ill 97 over Pecan Run Creek	1986	1,600	Good
Il 78 over Wolf Lake	2010	1,450	Fair
Ill 10 over Ditch	1927	1,200	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.