Illinois Bridge Conditions: A Deep Dive

Illinois is home to 26,927 bridges spanning 102 counties, making it one of the most significant bridge inventories in the country. These bridges carry a combined 137,500,040 vehicle crossings every day. Here is a comprehensive look at the state of Illinois's bridge infrastructure based on the latest National Bridge Inventory data.

Illinois earns an overall infrastructure grade of C based on the percentage of its bridges in poor condition. Currently, 2,563 bridges (9.5%) are rated poor, compared to the national average of 6.7%. The average bridge in Illinois is 46 years old, younger than the national average of 48 years.

Of the state's 26,927 bridges, 12,012 are in good condition, 12,352 are fair, and 2,563 are poor. View the full breakdown on the [Illinois report card](/reports/illinois).

These are the bridges carrying the highest daily traffic volumes across Illinois. High-traffic bridges are critical infrastructure -- their condition directly affects the commutes of tens of thousands of drivers.

The following bridges have the lowest sufficiency ratings in Illinois. These structures are the most likely candidates for federal repair or replacement funding under the Bipartisan Infrastructure Law.

Illinois's oldest bridges tell the story of the state's transportation history. Some of these structures have been in continuous service for over a century.

Illinois's bridge infrastructure grade of C reflects both the current condition of the state's bridges and the scale of the challenge ahead. With an average bridge age of 46 years, many of these structures are approaching or past the 50-75 year design life typical of most bridges. The state's ability to maintain and replace aging bridges will determine whether conditions improve or deteriorate in the coming decade.

For county-by-county breakdowns, historical trends, and individual bridge profiles, visit the [Illinois state page](/bridges/illinois) or the [Illinois report card](/reports/illinois). You can also explore how Illinois compares to other states in our [state rankings](/blog/best-bridge-infrastructure-by-state-2025).