Montana Bridge Infrastructure: A Complete Analysis

Montana is home to 5,235 bridges spanning 56 counties, making it one of the most significant bridge inventories in the country. These bridges carry a combined 8,590,648 vehicle crossings every day. Here is a comprehensive look at the state of Montana's bridge infrastructure based on the latest National Bridge Inventory data.

Montana earns an overall infrastructure grade of C based on the percentage of its bridges in poor condition. Currently, 388 bridges (7.4%) are rated poor, compared to the national average of 6.7%. The average bridge in Montana is 48 years old, younger than the national average of 48 years.

Of the state's 5,235 bridges, 1,682 are in good condition, 3,165 are fair, and 388 are poor. View the full breakdown on the [Montana report card](/reports/montana).

These are the bridges carrying the highest daily traffic volumes across Montana. 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 Montana. These structures are the most likely candidates for federal repair or replacement funding under the Bipartisan Infrastructure Law.

Montana'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.

Montana'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 48 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 [Montana state page](/bridges/montana) or the [Montana report card](/reports/montana). You can also explore how Montana compares to other states in our [state rankings](/blog/best-bridge-infrastructure-by-state-2025).