How Old Is the Average Bridge in Your State?

The average bridge in the United States is 48 years old. But that national figure masks enormous variation. In some states, the typical bridge was built during the Eisenhower administration. In others, most bridges date to the 1990s or later.

Bridge age matters because most bridges are designed for a 50-75 year service life. A bridge built in 1960 is now over 60 years old -- well into the window where major rehabilitation or full replacement becomes necessary. Understanding where the oldest bridges are concentrated helps explain why some states face steeper infrastructure challenges than others.

America's bridge-building history follows distinct eras. The first major wave came in the 1930s under New Deal programs like the Works Progress Administration, which built thousands of bridges across rural America. Many of those WPA-era bridges, now approaching 90 years old, remain in service today, particularly in Midwestern and Appalachian states. You can explore some of these in our article on [bridges built before 1920](/blog/pre-1920-bridges-still-in-use).

The second and largest wave began in 1956 with the Federal Aid Highway Act, which created the Interstate Highway System. Between 1956 and 1975, states built an unprecedented number of bridges to carry the new interstates over rivers, railroads, and local roads. States that built extensively during this era -- particularly in the Northeast and Midwest -- now face a concentrated wave of bridges reaching the end of their design life simultaneously.

Sunbelt states that grew rapidly in the 1980s, 1990s, and 2000s tend to have newer bridge inventories simply because much of their highway infrastructure was built more recently. States like Nevada, Arizona, and Florida built many of their bridges during population booms that came a generation after the Interstate era.

Not necessarily, but there is a strong correlation. Older bridges are more likely to be in poor condition, more likely to have weight restrictions, and more likely to be functionally obsolete (meaning their design no longer meets modern standards for lane width, clearance, or load capacity). The correlation between average bridge age and poor-condition percentage across states is roughly 0.6 -- a moderately strong relationship.

Some states with older bridge inventories have managed to keep their condition rates respectable through aggressive maintenance and replacement programs. Others have deferred maintenance for decades, and it shows in their numbers. The key takeaway: bridge age tells you about the challenge a state faces, but the poor-condition rate tells you how well the state is meeting that challenge. See the full [state rankings](/blog/best-bridge-infrastructure-by-state-2025) for more.