Bridge conditions in Mariposa County, California
109 inventoried bridges · 12 rated poor · 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
About one in 9 bridges in Mariposa County is rated in poor condition: 12 of 109 on the federal inventory, one of the higher shares in California.
- 12 of the 109 bridges in Mariposa County, California, are rated in poor condition (11.0%) in the 2025 National Bridge Inventory, as of .
- 20 bridges (18.3%) are rated good and 77 (70.6%) fair.
- The median Mariposa County bridge was built in 1956.
- The busiest poor-rated bridge is State Route 140 over Miles Creek (built 1928), carrying about 4,650 vehicles a day.
Good 18.3% · Fair 70.6% · Poor 11.0% 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 |
|---|---|---|---|
| State Route 140 over Miles Creek | 1928 | 4,650 | Poor |
| El Capitan Crossov over Merced River | 1933 | 3,416 | Poor |
| State Route 140 over Slate Gulch | 1926 | 1,400 | Poor |
| State Route 140 over Sweetwater Creek | 1926 | 1,400 | Poor |
| State Route 140 over South Fork Merced River | 1926 | 1,400 | Poor |
| 6TH Street over Mariposa Creek | 1950 | 1,080 | Poor |
| Triangle Road over Snow Creek | 1935 | 360 | Poor |
| Buckeye Road over Mariposa Creek | 1947 | 200 | Poor |
| Usona Road over Middle Fk Chowchilla Riv | 1970 | 190 | Poor |
| Old Toll Road over Bear Creek | 1948 | 130 | Poor |
| Winding Road over Middle Miami Creek | 1965 | 50 | Poor |
| Chowchilla Road over Big Creek | 1940 | 20 | Poor |
Busiest bridges in the county
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| State Route 140 over Mariposa Creek | 1932 | 10,800 | Fair |
| State Route 49 over Stockton Creek | 1967 | 7,900 | Fair |
| State Route 49 over Mariposa Creek | 1942 | 6,600 | Fair |
| State Route 140 over Miles Creek | 1916 | 4,650 | Fair |
| State Route 140 over Miles Creek | 1929 | 4,650 | Fair |
| State Route 140 over Miles Creek | 1928 | 4,650 | Fair |
| State Route 140 over Miles Creek | 1916 | 4,650 | Fair |
| State Route 140 over Miles Creek | 1928 | 4,650 | Fair |
| State Route 140 over Miles Creek | 1928 | 4,650 | Poor |
| State Route 140 over Miles Creek | 1928 | 4,650 | Fair |
Source: FHWA National Bridge Inventory, 2025. Counts cover inventoried highway bridges over 20 feet; ratings are reported by the state DOT.
All of California: California 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.