Why Covered Bridges Disappeared

Covered bridges declined in the 20th century due to:

• Modern materials: Steel and reinforced concrete enabled longer, stronger, maintenance-free spans.
• Vehicle loads: Automobiles and trucks exceeded timber capacity; covers added dead load.
• Road geometry: Wider lanes, higher clearances, straighter alignments incompatible with narrow, low covered structures.
• Fire risk: Arson and lightning destroyed many; uncovered steel/concrete is fireproof.
• Cost: Covered timber bridges cost more to build and maintain than modern equivalents.

Survivors (~800 in US) are preserved as historic landmarks, not functional infrastructure.